I agree, fenders can be Very dangerous because if they come loose they tend to get wrapped up in the wheel causing a lockup or the bike to skid on the fender making a crash unavoidable. I definitely wouldn't use fenders on a really fast bike for this reason alone.
One thing I've been thinking about if I ever decide to use fenders or if someone just has to have fenders would be to use a plastic fender or use the steel fender as a mold and remake it out of fiberglass. My reason behind this is that if the fender did come loose and get wrapped into the wheel it would shred to pieces instead of flip the bike at 30mph...
Maybe when I get more time to play I'll come up with a fiberglass fender that's strong enough to be fully functional but that would break easily if it hit the wheel.