Here's my two cents: I think there's a psychological aspect to all of this. Simply being ABLE to take better pictures because of better equipment aside, the subconcious knowledge of the abilities of your better equipment and the confidence that brings may help you relax and be able to focus more on composition and light rather than worrying about "I hope this camera can do this". Better equipment frees you up to "jump in with both feet" rather than timidly fiddling with camera settings in a (potentially) vain effort to "make" your low-end camera do something it probably can't do. And when the fancy camera ends up living up to your vision and succeding, you'll only get better and better. This is my experience anyway, and the whole reason my business is called "Freedom Photography".
Freedom Photography