No doubt, it isn't as simple as my previous post. But particularly unnuanced and poorly argumented remarks like "we don't need stupid upgrades, we need new bodies!", just call for unnuanced replies
. He didn't give one clue as to why "we" should need new bodies.
I know countless people who are a little bit addicted to gear, and spend not nearly enough time improving their skills. No matter what gear you have, it's still you that has to take the pictures. Newer / better gear can make things easier, of course.
I myself upgraded from a 450D to a 7D because of the ergonomics and things like the jog dial and wheel to make things a little easier. Does the 7D make me take instantly better pictures? Not that much. I've a long way to go until I reach the limits of my gear. Will I upgrade to another camera before that happens? Probably. Do I need to? Probably not.