I have played DDO off and on from launch and now 10 years in I see the game struggle to stay relevant.
The graphics engine is old and you can only invent so many ways to use kobalds.
For this game to get back into it's stride, the owners need to go back to what made PnP D+D great.
PLAYER CREATED DUNGEONS
OK, how can we do that in DDO
Embrace Planescape and the city of doors. The PERFECT Expansion to house player constructed adventures.
If you are not familiar with Planescape, look it up...not going to try and do that here.
The tools that the player (subscriber) uses to make an adventure in the city of doors should have
the following qualities.
1. Adventures are self-level adjusting. Any adventure made should auto-adjust to the party level.
2. All chest/rewards should be self generated based on monsters present and not set by author.
Author should be allowed to designate possible chest spawn sites or let the dungeon creation engine do it for them.
3. map parts should be easy to use...snap together.
4. ect..
This will breath in new life and new material.
This suggestion is 'bare bones' and there is a lot that would need to be worked out...of course.