The fact that you will also have to put the PC together is another consideration. It's not something everyone can do. If you don't want to put it together yourself, you will have to go through some builder who will charge you $50, and if you're not well versed on pc parts, you will have no idea what in the world you are selecting. Gaming pcs are a rather niche market, and although I really enjoy gaming on the pc to the extent that I hardly ever turn on my console (PS3) anymore, I can understand why a lot of people would simply prefer to turn on a console. Not everyone has the performance guru/tweaker's mindset where they enjoy getting as much performance as possible and aren't afraid to spend the time and money to do so.
For the most part, I feel that graphics will be more contingent on budgets than anything. Sony could have went with that exotic design which probably could have pushed out even more results, but developers wanted them to go simple, which is what they did. When you start developing games at the fidelity they currently are, it gets very expensive. We will have plenty of gorgeous games this generation.