I feel like people truly advocating for the removal of flying mounts are just looking for something to complain about. Traveling everywhere on foot at level cap gets tedious, but flying while leveling detracts from the experience to get more WOW gold. They've struck a good balance in the last few content patches and I don't see a reason to change the formula any time soon. Besides, I like my Ironbound Proto, but I also like having an excuse to break out my Fiery Warhorse or Magic Rooster.
Removing flying mounts would make me come close to cancelling my account. There are aspects of this game that are more fun with them. Archaeology and resource gathering has being top on the list. Not only does it suck to be killing mobs to get some WOW gold as well as get to a resource on any type of server and somebody else steal it from you, but it sucks having to clear it just doing something as simple as archaeology. I don't know what rock these mouth breathers who are crying to flying mount removal crawled out from under, but they need to climb back under it and an asteroid needs to fall on top of it so they never return.
I transferred off a pvp server because I was tired of my pve (questing, dailies) experience being marred, not by "world pvp", but by individuals that would gank me. PVP is not balanced on an individual level, so the ganker almost always has the advantage over the gankee. Having flying mitigates that somewhat, as you can just mount and hover in the air more than 40 yards up...unless there is a druid around who can chain moonfire/flight form you until you're dead. That all said, now that I'm on a PVE realm and I already get enough WOW gold, I'm happy although a little weirded out that I can't attack the opposing faction unless they flag themselves.
I think not having flying in designated pvp zones is a good idea. Leave flying alone. Add aerial combat for those that are flagged. I don't think removing flying mounts will ever happen, I have no problem with certain places being ground only or not allowing flying until max level, but I do recall blizz saying that something about an item or WOW gold that will dismount someone so they can't just troll you and fly away. Now that is something I would like to see... Although I do think mounted combat is way over due!