About 80% of the Glock owners out there run a stock weapon.
They are the "casual owner" just like those for, say, buy a Mustang/Camaro for the power and flash.
Then you have the people that "rely" on the weapon, the forward progressives, the fanboys and the competition shooters.
They make the mods that you are talking about because they MAKE SENSE. They address a secified change to budget constraints imposed on the production piece by bean counters that didn't care about your safety, only the bottom line.
"Plastic" guide rod (sorry, polymer
)?! That makes NO SENSE to me as a gun owner.
Why would I want that?
What possible purpose could that serve ME as the end user of the product?
Things like an extended mag release or an extended slide release button have been "upgrades" by the 1911 platform for dozens of years.
Yes, sorry folks, but innovation follows tradition.
If I were to buy a Glock, and wanted to carry it because it was light and 99% reliable? The first two things I would change would be the guide rod and the trigger.
And I am barely an apprentice in the world of gunsmithing.