They were designed to provide more grip surface. On the square range, it probably seems useless. But in a drill, competition or shootout, with a malfunction that prevents the mag from dropping free, they can be very useful. A failure to feed that locks the gun up, sometimes requires forcefully stripping it from the gun. The Vickers baseplate and others like them, are designed to give you more surface area to grab if you need the magazine out "right now" and it fails to drop free for any reason. Clearance would involve a slide lock, strip the mag, rack the slide several times, reinsert new mag, rack and bang.[/Q
The only time I have EVER had that happen with a Glock is when it was set up with dummy rounds. Now with a ppk....