The problem is that techies are used to the cowboy coding and hero atmosphere. They use their technical knowledge to essentially hold their bosses hostage and foster a "no consequences" environment. The minute you bring in a PM who attempts to get estimates and hold people to dates, you get techie temper-tantrums!

On the defense of tech workers, you often get too many PM's who have a one-size-fits-all approach to PM. PM practices need to be scaled to the size of the project. Keep administrivia to a minimum!