I think there is nothing wrong with upgrading for graphics.
But there is nothing gameplay-wise, that the new systems can do that the old ones can't. Unless you count better kinect or whatever. If you say there is something, you are wrong. Older systems could do it, it just wouldn't look as pretty.
Last gen the jump was more pronounced. Wii had motion gaming which was really cool at the time, and PS360 introduced HD graphics which were a dramatic jump if you had an HDTV. Also, online experiences took a major step forward and games could also be downloaded. Past system games were now available too. This was all very major and crazy stuff that wasn't available before. Nothing on the new systems compare.
But that doesn't mean the new systems aren't good or worth it.
