I'm well aware of the rear cutout and why it's there. But using that technique requires the shooter to place the weapon in a holster, between their knees, or somewhere else when removing the magazine with one hand/arm disabled. Holding the pistol like you hold it to shoot, then hooking the extended floor plate on a hard object, you can quickly and easily rip out the stuck mag. It's significantly more effective than what you describe doing and the way shooters used to have to do it. It's also why companies like 10-8 and Tango Down sell floor plates that extended on the side - for leverage when ripping out a magazine. Right or wrong, we have lots of shooters who put a plug in the rear of the Glock (for a variety of reasons). The half-moon cut and Gen 5 mags allow the gun to still be operated one handed when using a plug or OEM beavertail which takes up part of that space.
You may find the baseplates from the Gen 5 guns "weird" or unnecessary, but plenty of armed professionals and people who train appreciate them. They are an evolutionary improvement. If they pinch you on a full size gun like a 17 or 19X you must have hands like Andre the Giant. Even then, I have a hard time seeing how they interfere with reloads, but the previous generation base plates don't, unless you are wrapping your pinky finger under the magwell. The good news is Glock sells the magazines with either option, and replacing the plates is easy.