Many is an indefinite designation. My point was that it wasn't melee-centric players posting in favor of this, but people who are (prominently, in some cases) fans of playing casters.
As for the people who are against this, many of them will always be against any change to the game that makes them weaker, or forces them to work harder, or play smarter, without concerning themselves at all with considering the problem and irrespective of the proposed solution. Most don't acknowledge that there even is a problem, which is totally ridiculous. Many people call for better AI as THE solution, but doesn't acknowledge that it may not be possible (at least right now).
There is a problem. If this could get fixed by improving AI (and if that were a feasible course of action at this time), I'd prefer that to basically any other change, but that seems unlikely, since such suggestions haven't gotten much dev response ever, and this thread is not the first time the topic has been brought up. But people also ignore the fact that simply improving AI won't necessarily solve anything, because a couple of the problems also reside with the facts that no AI is going to be able to adequately challenge tens (or hundreds) of thousands of people all sharing information and experiences, and because we all learn the game pretty well through repetition. An "AI" solution would require improving the way monsters react to us, randomizing their responses, actions, locations, types and buffs, and introducing far more significant randomization into quests, so that we can't say when we step in what route to take, and where the shrines are, and what spells will be the most useful, or the most useful here, and the most useful there. That's a lot of work for a relatively small development team, and may be too much for the current DDO system (code, servers, etc...) to handle properly--remember, AI has a lot of overhead and can lead to more of the lag that all of the same players are constantly complaining about on the forums.
The problem doesn't exist just because a vocal minority of players have complained about something--the devs quite obviously have acknowledged this problem for a long time, which is why the original epics had blanket death spell immunity, and even after removing that portion of Epic Ward in most quests, they returned it in epic challenges, and proposed Hard to Kill in the first place, and rather than dropping the idea entirely when met with such overwhelming negative reaction to it, they instead proposed another solution. It should be clear to everyone that the devs feel that the ability to instantly kill monsters, and especially groups of monsters, with ease is a problem.
And if you think the devs' opinions are simply tugged this way and that by a small group of players, like so many marionettes, then you are sadly mistaken. Just look at all the archery discussions that the devs have commented on for the last 6 years: nearly every player to post in such a thread has mentioned that they feel that ranged combat is much too weak, while most dev comments have indicated that they are hesitant to improve archery, despite having (inadvertently?) made a beast out of a similar style in the form of artificers, and while ignoring the fact that casters are 10x as strong as any archer would be even with major buffs. Clearly not listening to ANYONE there.
So how do we solve the problem? Some people want longer cooldowns, which just means you get to use death spells less often. Period. Some want monster's saves to just be increased, while ignoring the fact that that carries all sorts of other negative consequences with it, like gimping the abilities other classes have (Assassinate, Trip, Stun, Touch of Death...there is a long list). Others liked the original Hard to Kill idea, even though it made using instakills almost completely pointless. So what solution is there? What will work without completely screwing lower-DC casters, monks, rogues, paladins, rangers, fighters, barbarians, bards... and without making Spell Focus: Necromancy a waste of a feat slot, along with everything that stems from that?
I wanted Deathblock and Death Ward to get changed in the same way that Neutralize Poison did in regards to death spells and effects, replacing immunity with a bonus to saves and a "no fail on 1" clause, in part because of the issue here, but mostly due to the larger issue of immunities ultimately being bad for the game. We didn't get that. Instead, we got a system that allows casters to keep using their spells, but forces them to do so tactically, or they suffer penalties for a short while (that they can power through if they are very well developed). It retains the value of being able to kill lots of things quickly, but limits that power somewhat. Do you have a better, likely solution?
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TL;DR Many players simply refuse to acknowledge that there is a problem. The devs clearly feel that there is a problem all on their own; it isn't simply due to a vocal subset of players convincing them of this. Improving AI isn't as easy a solution as everyone seems to think, likely cannot ever be enough to sufficient challenge such a large group of intelligence-sharing people, and may cause a significant increase in lag.
The Haunting solution maintains the usefulness of the ability to kill many enemies quickly, but puts a damper on doing so too often, forces players to play tactically, and doesn't incidentally nerf a bunch of other characters in the process.
If you really don't like it, acknowledge the problem and propose a reasonable solution (ie., one that doesn't hamstring the playstyle more than this does and doesn't have a lot of collateral damage for other characters, while actually addressing the existing issue). Calls for "just leave it as it is," and, "there isn't a problem here," are short-sighted and ignorant.