I have a fairly decent connection, but, as of now, Cloud gaming is pretty much unplayable. Unless it's something like turn based.
Gaming is different than videos. I'm probably going to be playing a game for at least a couple of weeks, so an up front install is not a big deal. And, I'm also rarely in situations where I need to play a particular game right away, or just want something to have playing in the background. It could make sense for other people, if it can be done properly, but for "hardcore" gamers, it doesn't make a ton of sense.