I pre-order just to get it out of the way, more than anything else. I know I'm gonna buy it eventually just to stay current with the game, and personally I'd rather pay real money now than crowns later (even if it does work out slightly cheaper that way). ZOS wants to give me bonuses for something I was going to do anyway, so why not? It's more convenience-motivated for me, rather than any kind of impulse or temptation thing, though. Now it's done, and I don't need to think about it again.
Unfortunately, though, I am a sucker for Outfit styles... so they roped me into the Collector's Edition. I don't care a whole lot for the mounts and pets and other whatnots on offer, so it's a bit steep in that regard.
Probably not that many Nagahide mounts are running around because they are terrible to ride. Unless you like seasickness.