In my opinion, leaderboards go against the spirit of D&D. D&D is always about cooperation, about how a group is greater than the sum of its parts and can overcome all kinds of external challenges.
Yes, I know DDO has strayed far from its roots, but it's still a PvE game, not a PvP one.
But hardcore was a cheap and lazy solution (requiring hardly any work) for implementing events, so it debuted for that reason and has persisted for that reason. And that's probably why it won't change, even though a large part of the population isn't interested in permadeath mechanics or starting new characters.
That said, leaderboards don't bother me. I think they're fine if someone is interested in them. What bothers me is having to create a new character when I've had to store my alts due to lack of support, and permadeath mechanics, which I dislike. These mechanics force you to play it safe, not to have fun, and force you to use only "tough" builds, not the builds you enjoy. Permadeath is a playstyle for a select few, and it shouldn't have special rewards that can't be obtained any other way.