I once asked an instructor why he used a Glock 19. I said that the 40 S&W was a little more potent. His response was that a perp would see little difference when hit with a double tap 9mm versus my 40 S&W M23 Glock.
Glocks really aren't bad guns. They function very well and are easy to take apart if you need to.
Don't judge a book by it's cover.