Good post, nobler, I agree with much of what you say. There are some throwaway zones in Vanilla, and while none of the zones in Cata were that great, Jade Forest is an absolute stunner. I can't really say the other MoP zones are particularly mind blowing though.
But to your larger point, yeah, you're right, players can choose to play however they like. I love the idea of traveling to a summoning stone and doing it old school. Problem is, just about nobody else would find it fun! Most people will take the easiest possible option. And I understand that.
I suppose for me it probably boils down to not being able to recapture that feeling when I first started the game. No matter if it's a new expansion, cool content, new challenges, nothing will compare to being a low level noob learning the game one mistake at a time with a fun group of people.
Waxing nostalgic over here...