Not entirely sure but I believe you can still do the quests?

Also, even if you do get the mount from WoW-Mania. You won't be getting the Felstead (?) I don't think.
While doing the quests you also gain exp and gold. Plus you get motivated to explore more parts of the world.

Most instances require pre quests.
Besides that, the game wants you to explore the world. It would be quite boring if you were just handed the quests without effort.

The problem may be that the AI is too smart with their lightning reflexes to instant pop shields and renews on ppl. And the movement can be quite difficult to path. If the healer block himself with line of sight the whole time. That can be quite annoying. Guildwars has a near henchman system. It wor...

I know you can enter Onyxia with attunement. But there are people who would like to do it the vanilla way.
I don't get the right quest to pop in Blasted Lands to start the questline for Attunement on Onyxia.

It's the one that ends up with the Drakefire Amulet if I remember correctly.