The problem is that most people don't use them correctly. They think they can just jump from their supportive, super padded running shoes and pound out the same mileage not giving their jounts, tendons, etc time to adapt. That, combined with very few "runners" practice good running form or have naturally good biomechanic's, has led to a lot of injuries.
That and the fact that I personally don't like the look. On that note I am going to give the more minimalist shoe's a try as part of my shoe rotation. I am getting ready to test some Brooks Grits as soon as my sponsors get them in.