I can see why it happened, obviously, with Mark Henry's (apparent) injury. Big Show probably wasn't in line for the title anyway, so having him win then Daniel Bryan cashing in on him gives them a go-to feud, with some Mark Henry involvement, while lessening his load. Makes sense all around. It was definitely a good moment too, seeing Daniel Bryan, the indy icon, finally grab that brass ring. He has worked his ass off for years, so as a fan of his, I'm happy to see it happen and happy to see that he wasn't, in fact, the first one to lose his bid at the title.
Some people may think it's too soon and it probably is, but they can still easily legitimize Daniel Bryan with a couple of good defenses. They could play it off as him defending what is rightfully his and so on. The crowd will get behind it and when your WrestleMania is going to be carried by John Cena vs The Rock, you can afford to have Daniel Bryan go in as champion, to further test the waters. The thing is though, the WWE have to be confident in Daniel Bryan. They can't have this pan out like Jack Swagger's reign did, they have to follow it with good booking, but they also have to showcase Bryan's talents, which he has plenty of, and his readiness for his spot.
The dynamic between Big Show and Daniel Bryan will be something to watch for, as this is somewhat Big Show's fault. There's no clear cut heel or face there, but if Big Show tries to impose his will on Bryan or blame him for what happened, it opens the door for Bryan snapping and becoming the crazed submission machine he can be. There's lots of potential there and that's discounting Mark Henry's presence. As far as I know, his injury that apparently set off this title change isn't too severe, as he could have worked though it (with a lighter load, of course), so it'll be interesting to see where he fits in. If healthy enough, I can see him being involved in the WrestleMania title match, which I'd imagine would be a fatal four way with Bryan, Show, Henry, and the Royal Rumble winner (possibly Sheamus), unless a Raw guy, like Dolph Ziggler takes it, in which case it would be a triple threat.
Good stuff by the WWE.