There's a lot more that can be WOW TBC Gold added to this fundamental idea, as well as many more aspects in vanilla that created an excellent basis, yet I've not yet seen a follow-up.
I'm aware that there are problems with this design that need some sort of solution, for example the differences in the levels of players of the highest level, fresh cheap Burning Crusade Classic Gold characters or faction imbalance. I am now aware of the potential of WoW however it was an already fantastic game.