I'm not sure there are words in the English language that can properly describe how bad some of these ideas are.Sorry but Raiding is not end game, running content for only gaining loot that has no meaning because your already in the highest lvl content already. We know the game will cap at 30, with that limit now stated we can assume content for that lvl will be the limit on powerful items we gain. The fact is its only ED and their ability that is worth playing the game to develop at this point. Its new ED and more twists slots that will keep players wanting to play to develop those abilities further.
However Raids need to be seen as the flaw they always where because simply put if you see yourself as a hard core raid gamer you are on the WRONG game period. Go back to WoW but likely your here and not there not due to not liking that game but actually being a wowtard, someone who likes what wow does, but cant handle wow so goes to another smaller game and try to turn it into wowlite.
The one thing WoW absolutely does best is raids, some other MMO try to and come close, all of them are the logical choices for hard core raiders, one of the most toxic part of DDOs community, and nothing about DDO would be hurt by those players finally letting go and moving on.
No what DDO needs to do to make replaying it as a new alt or a TR is open up all content to all lvl ranges, this could be done simply by adapting the mechanics of challenges to all content, making no content for specific lvl ranges at all. Like wise named loot could have varied set effects and additional augment slots added based on the lvl of the content being set.
Imagine if every alt, every life, you could pick what content you found most enjoyable in DDO whenever you wanted, at any lvl and run it for xp and loot. If no longer was content as end game themed as the vale was forced upon us in the mid teens and lvl 20+ content included wolves and other out of place elements for an adventurer looking to see otherworldly things could be chosen to be run at a lvl range that made it feel appropriate. Imagine how it would let us be able to govern and add to our individual play experiences.
For example there are many quests in house K for example that feel often like they should be higher lvl simply based on the context of what we are doing, likewise there are many quests in the realms for example that to me feel like they would be far more applicable from a personal story experience to be run at much earlier levels.
For a simple way to spell it out, if it has wolves and wild life that could in no sane way challenges a mighty warrior or well versed master of magic, id personally always try to run such content prior to lvl 10, and content that involved things like sentient undead, evil casters, and outsiders for my lvl 10-20 phase of playing.
Even parts of Korthos like its final adventure to break the crystal while the dragon fights the mindflayer could become a worthy high lvl adventure in such a system.