because unlike Nintendo, I know what I'm getting with Sony. I know I will get a fairly powerful console (possibly very powerful knowing them), I know I will get a stable online system, I know it will likely be free, I know there will be a big hard drive for installations and downloadables, I know that I will be able to use it as my main box for playing bluray movies/games/whatever else, and probably most importantly, I know I will get TONS of exclusives from 1st and 2nd party studios, the likes of which you will never see else where (such as team ico, naughty dog, etc...), most 3rd party games as well will obviously be on it, and the list goes on.
There's little to no worries with them. I'd say the same for 720 though I don't like Microsoft's exclusive offerings (or lack thereof) and their kinect future, also don't like paying for online, that's why they aren't on my list. But PS4 seems like an obvious insta-buy eventually.
Nintendo has time to blow me away though, it's up to them. What I want to see from Nintendo is a strong enough console to keep up as close as possible to PS4/720, a stable and robust and free online system that works across all games simply, lots of money hatting of games on their console, and the one that worries me most, Nintendo of America to actually give a shit about customers and bring some games to north america that I want to play. I have no faith in them.