This is one of those 'big' suggestions so those who don't like walls of text should skip right over it. It is also one that would take significant developer resources and a lot of new blood over at Turbine HQ. As such it's one of those very long shot ideas for ever seeing the light of day. So onto the suggestion.
I propose a 'reboot' of DDO. Essentially this would be 'DDO2' with fully transferable characters from DDO 1 and almost all the content from DDO1 being still usuable.
The main points of the reboot follow:
* Expanded and long term license to D & D properties in an MMO setting. This would include the various campaign settings and suplementals in D & D. FR, Greyhawk, and dragonlance are all classic D&D settings that have broad appeal to legacy gamers. They also have strong lore and classic sub-settings associated with them. Planescape provides a perfect setting to integrate various worlds and lore into a single game. Ravenloft and Dark Sun provide another asset with their strong themes. Ebberron which we have been kicking around in for the past few years was a new setting with no name appeal that really had as it's main appeal a more psuedo tech feel with robots for the younger kids as a selling point. There is no reason (besides the intellectual rights) that a DDO MMO could not and should not include the various settings given enough developer resources. In this way the appeal of DDO would be much wider due to it's inclusion of the various settings and their widely differing feels.
* Legacy characters and content would carry over into the 'new' game. Essentially one day ddo would go down and the reboot would come up the next day. No two game system required or wanted here.
* Introduction of 'world/plane' rules in a wider sense. Instead of a tack on buff that does very little allow drastic alterations to the rules based upon the dungeon where appropriate. This would also include stuff like 'mythal' rules where certain spells might be more powerful or unusable for example.
* Elimination or rebalancing of various tacked on mechanics added to DDO. Let's face it most of the tacked on systems in DDO don't work right or have serious negative consequences. Dungeon Alert makes little game sense, requires hand crafted adjustments to it if it actually is to work to some degree in certain dungeons, and makes trivial mobs and dungeons slower and more 'grindy'. Dungeon Scaling actually creates a reverse incentive to grouping and would need serious adjustments to not have this largely negative effect on the game. Grazing hits was a bizzare juxtaposition to fix AC without actually addressing the real issues with it. TR's encourage grind >> challenge and need lots of work on their basic mechanic of leveling to fix this dynamic. Epic content seems to be without a clear vision, has tons of ill thought out special rules, and frankly is set up as a grind until you bleed mechanic.
* Long term fixes that allow for long term scaling of various systems that in classic D&D break down. These include AC, saving throws (have not yet hit this point, but will with continued scaling), skill checks, and ability checks. Many of these we have not hit the point of no return on yet, but with further scaling we will see more and more issues. Essentially at the heart of the issue is the d20 system. Statistical distrubitions or other creative methods that allow for no 'falling off the dice' with more gradual loss of effectiveness will be needed here. All this of course is about leveling beyond level 20.
* Fixes for badly implemented basic mechanics or mechanics in classic D&D are not very well thought out. These include ranged combat (specific powers/PrE's...are band aids and not helpful in the long term), large scale immunities on specific mobs (red/purple named this stuff is useless all of a sudden issue that we have seen lots of suggestions about how to address in specific cases), random loot tables (due to implementation random chest loot is horrible beyond a certain point and there are tons of posts to explain why this is), non scaling or too gradual scaling in some item classes, the concept of acceptably bad loot (needs to be eliminated completely...no named loot should be bad for it's level as then it is merely a waste of development resources), lesser utility of certain ability scores (int, cha, dex), xp rewards and the diminishing rewards for higher level quests. That is a laundry list of stuff that really has some basic design issues surrounding them. Often times they are issues that developed due to developer expedience or worries (ranged combat can't be good because people might exploit our bad geometry for example). Other times it is stuff that carried over from basic D&D into an online MMO badly (cha matters more in a roleplaying game then in a computer game...). Some of this will be easy to do...most not so much.
* Fixing spell casting. This point concerns the basic mismatch of utility of certain spell types compared to others such as instant damage to DoT power houses as well as the vast and unnaceptable mismatch between spells of the same type. For example, Acid Cloud does horrible damage compared to Fire Wall yet one is higher level then the other and they are both DoT type spells... Lot's of ways to address these things that have been discussed on the forums over the years.
* Refocuse of the game away from Ebberron to a wider view of the DDO universe over time.
* Robust back up methods and automatic corrections of lost data from bugs. Lost items still might happen, but they would get restored automatically every X days instead of dispearing into the ether forever. This is a big one when it comes to long term customer satisfaction and also identify these pesky bugs so you can fix them.
* 'Hand Crafted' no longer... This concerns the development of powerful data structures within code and development suites that encourage the re-usability of code and ease of entering new things into the game. Instead of hard coding in new enhancements the process should be as simple as filling in some data base fields (new extra unique abilities would be coded in still, but in a manner that new uses of them or altered uses of them would again just require a data base entry). Lots of good stuff here that can be done all in the effort to create a drastically streamlined and less error prone path from concept to implementation of new content.
* Calculated statistics. Nothing in game should be implemented based upon a 'this feels right' attitude. Math should drive the decision making process when it comes to dungeon design, ability design, item design, and rebalancing of any sort. To help this process along powerful math based evaluation programs should be developed to evaluate existing conditions as well as any proposed new development effort. Math based goals should be established for design efforts. If TWF is seen as doing too much dps the developers should know exactly what dps is done by different builds with different gear and in different content. They then should be able to determine exactly what their desired goals are. These goals and metrics should be the go to explanations when explaining new stuff coming into the game. With scripts meant to gather/calculate all sorts of interesting data the developers can quickly see the exact math behind their goals. This is not by any means limited to the systems team. These tools would be incredibly powerful in the hands of dungeon designers, particularly if statistical data about average completion times and such was included in a manner that would allow the designers to extrapolite (or even better have the scripts do it for them) these expected numbers based upon their current dungeon setups throughout the design process. As a huge part of this all this data for the current live version should be available to the players, some in game itself (like dps with current gear setup versus certain mob types) and others through an expanded interface of the wiki and MyDDO.
Lots of these things will require tons of work. Many of them will make DDO into a game that has a potential lifespan drastically longer then otherwise by addressing game mechanics that have scaling issues and increasing the efficiency of development by requiring less work to essentially be redone. The conversion to the hybrid system of payment revolutionized DDO's finances. I think DDO would do well to reboot the rest of the game. DDO2 should be DDO: + and not an entirely new game wasting most of the development effort to date.