People don't even read the OP... He puts clearly that to buy levels you'd need to have several max-level characters and an account with more than one year. Under those conditions, I see no problem.
You see, I have 5 level 90 characters (Paladin, hunter, priest, warrior and mage), and 4 more at various levels (shaman 40, Warlock 61, Death Knight locked at 80, Rogue at 52). Sometimes I want to try something different, but really, it's hard to redo all the leveling proccess again. I think I've done every quest in every zone save for the second part of Zul'Drak.
I don't see the problem if I for some reason decide to pay to get a character at 85. I've already experienced the game enough, and most content and activity happens at max level.