The Withered Army Training is the best solo content I've ever done in the game period. :/
Yes, it'd need some tweaking to account for class strengths/weakness in a another iteration (Dro was too problematic for some classes initially, and tanks get off far too easy) but that's not a reason to do away with actually interesting and at least initially somewhat challenging solo content. Guess we'll never get another iteration, though. I've played with so many unbelievably shitty players since the expansion has launched that I can understand why, but that still bothers me. Hopefully, brawler's guild will fill the gap.
Only thing I can't stand about Withered Training is having to farm up the mana constantly. Its so mind numbing.