Let me counter all of your arguments.
1) I have said it is a convenience, that essentially degrades the game experience. Go read my other posts and try counter those firsts.
2) That is because the game is designed to accommodate for flight now. They need to make higher level areas inaccesible to lower level players, and one of those techniques employed is putting the higher level mobs onto a higher plateau, making them inaccessible to players without flight (namely, lower level players).
This retarded argument only holds any water if they don't accommodate for the lack of flight in WoD zones.
Flight paths are there as a means of fast travel and they were largely rendered pointless due the addition of personal flying mounts. When newer features in your game start rendering other parts of it pointless, then you, from a game design standpoint, are wasting resources and you fucked up.
And here is the stinker again in your argument. You say you know nothing about game design (as if it wasn't abundantly clear in your posts) Therefor you should refrain from speaking your mind on the subject because 9 times out of 10, you'll blurt out retarded statements like this.
If this is your reason as to why flying mounts are a KEY component in your style of play, I'd suggest looking up the definition of the word "key" in this context.