Tank Achievments and Flying Mounts

Small thought had crossed my mind while farming up for the Dark Knight achievment mount. I was never gonna really use it. Its a ground only mount, and while it is really cool, I'll never really be able to show it off. So wait, why can't they just add another achievment after the last one, and give them flying mounts right? Seems like an easy enough suggestion. :)

Yeah like: 500 Times 8-man, get a flying mount.

That would actually suck right now as something that would reward a flying mount would require x amount of 3.xx high level full party instances and currently there's the 2 ex fights, I can't see Alex normal being considered ex equivalent