I think that legend dk's and paladins are pretty balanced. Certainly being a Rose pally gives you a massive group support option (freedom). But getting nightfall is even more useful, especially if trying to run zones you have no business doing. The difference is that nightfall is more of a general zoning support option, while freedom is an "oh god we are about to mass-rip" support option.
If your issue is that dk's need a bigger challenge and a more interesting quest to get the same skills I would suggest you apply to be a 31, help people out at every turn, get creation port access, and start writing one...or just find a buddy who has already done that and write all the rdescs for them and give them a walk-through of the quest and let them take all the credit. Mind you it will probably be over a year before it would ever be put in the game. After all, the people coding this stuff are doing it for free.