I am a shop-a-holic and, normally, I disagree with every single thing that you post. Every. Single. Thing. So mark today down on your calendar, because today is the day I break with that tradition by saying that I share a lot of the same doubts as you.
I own a lot of D&D and d20 3x material that works in ways that I like. I also own several other systems that I like and that are specifically suited for Fantasy modes and genres not covered well by D&D (e.g., HarnMaster, The Shadow of Yesterday, etc). I further have a wealth of generic systems (e.g., The Window, Risus, TWERPS) that potentially cover any genre and setting that I apply them to.
I'm not really sure that I need D&D 4e. Monetarily, it isn't looking like a good investment for me right now, if only because it doesn't seem to do anything that other systems on my shelf either can't do with ease or don't do by default. Right now, I really like how D&D 4e seems to be shaping up -- but do I need it? I don't think so. I'm not sure I even want it, really.