Animations are no doubt the main issue..
I'd also argue that in general a weapon should have some strategic or numerical purpose in game. We have lots of DDO weapons no one uses because they simply don't offer any kind of advantage and seem to be in game just becasue it was easy to model them and they could share an animation with other items.
I'd say spears/pole arms do have a good purpose in game with two handed pierce etc... I think asking for reach and the like is a bit out of the scope of what DDO combat offers since few weapons really have an actual reach advantage currently and having a 5' dead zone on poll arms would be problematic for everyone.
Some of the other weapons like flails would be a lot of work for no real in game benefit since its basicaly a morning star wtih different graphics in D&D. Same goes for lots of other weapons.