Glock makes Pistols, but engineers and designers, don't carry them, we the gun guys do. So we use mods that work for us, to enhance the performance, so as to make them work, for every day carry, or even in the extreme of going to war.
As individuals who can bring many years of carrying pistols in harms way, we can add items to our go to pistol, that Soldiers can not, to make them work for us.
For instance my G19 4th Gen pistol has a set of TruGlo fiber optic sights, extended slide release, Glock original equip. Short frame plug, makes mag changes better, blocks crud from action. Smooth trigger release up, change to smooth faced trigger, 4.25lb weight. I am totally at peace with this pistol, have shot countless rounds through it, no malfunctions, use 147g Win. Ranger T. But in the past, I have shot 1000 of rounds of Mil Spec 9mm, Sten Gun ammo (from a Browning Hi Power) and would be totally happy with 16 rounds of Sten gun ammo in the Glock. Plus two extra 17 round magazines.