With pets, mounts and everything else shared across my account Blizzard has taken away a huge part of my enjoyment of the game of WOW.
The reason I create several different characters is so that I can have a different experience of the game with each character. Having each with their own mounts, pets and achievements etc.
The way the game is now to do that I would have to create one character and play it as far as I can then delete it to create a second one to get the different experience that I want to get.
This has put me right off WOW which has been a game I have enjoyed for a long time - untill now.