The Colgan pilots with 300 hrs when hired had the basic training to get through the instrument and multiengine training and commercial.
Teaching stall recovery and botched landing recovery for a couple thousand hours instructing students sure sharpens up your basic flying skills. That alone will make the 1500 hr requirement make the commuters safer. 300 hr pilots are the most dangerous because they have all of the licenses but don't really know how to fly yet. I was crop dusting then and had a bunch of close calls flying under wires and landing with leaves on my struts and gear but I could only kill myself. Also the Super Cub was barely fast enough to kill you. CFIT in a jet is a lot worse.