Actually, it looks like it's being done to make it control method to be a Cata exclusive. Those without the Expansion will be unable to buy the skill. Also explains the trivial price.

I'm going with Rudzy on this and a little of the first post up there. 1-58 you don't really need a flying mount. Really couldn't get it anyway. With the way leveling goes and costs, you should be able to buy the flying skill somewhere within 58-80.

At that point, you can level through Northrend without flying, so you can skip Cold Weather Flying and can just get Old World Flying and a rather cheap price. If you skip CWF, there is really no excuse not to get Old World flying.

Magius,

You have to consider the tome of cold weather flying though if you already have an 80. I know I would be tempted to buy a tome of cold weather flying to level an alt through wrath. Questing is sooo much faster with flying.

@SunGod
That is a consideration. I was going on the assumption of a brand new character with absolutely no support. I should have put that in my original post.

Yes, if you have an 80 already in place, there is really no reason not to get each riding skill when it becomes available. I'll leave epic flying out as it is really expensive. Epic flying is nice and all, but you'll be fine if you don't buy it immediately.