From what I have seen, 4e is not to my tastes - not to mention the huge investment I have made in 3/3.5 materials.
First, it seems like a power-gamer's dream (nothing wrong with that - just not my taste). Also, I have more than enough material to last me for years. I see no reason to abandon that investment or do all the work to change them to 4e.
I realize 3.5 is not perfect but it basically works with some tweaks. I don't want to make the financial or time investment for learning a new system, and having to figure out what does not work and tweaking it. Face it - no way that a perfect system can be made.
I understand that WOTC is trying to get more folks playing D&D, but I am happy with what we have now.