Gustav of Nazjatar started a long thread the other day about air kills (and many times, the lack thereof) in World PvP. These concerns got raised before the expansion, but I haven't heard too much about them since until now (maybe that's what I get for playing on a PvE server). Basically players are saying that when you get a flying mount at 70, you suddenly become immune to PvP-- because there's no way to pull people out of the air, a flying target is no target at all. And that, says Gustav, is yet another example of the "carebearization" (nice) of world PvP by Blizzard.
The other issue Gustav has is an upcoming change that will make dead players' bodies fall to the ground after death, instead of remaining suspended there in the air like, as Drysc says, "a magic trick gone wrong." Blue's word on this one is that it's just not "natural" to leave players in the air-- Gustav thinks it's because Blizzard wanted to give people a break on repairs (because now, players left in the air have to rez at the spirit healer), but Drysc says it's just artistic-- let the bodies hit the floor, man.
But Gustav's more interesting idea is that every class should have an anti-air ability-- a way to bring your PvP opponent out of the air. To my mind, that kind of thing just opens the door to griefing-- actual air-to-air combat seems like a better idea to me. Drysc's response to the news that PvPers are avoiding a fight by flying sounds about right: staying on a mount when someone below is taunting you just makes you chicken. If you're really interested in world PvP, then get off the mount-- it's time to drop down and throw down.