Actually, the thing about the sights is that they seem to be "softer" than the polymer of the frame.
The deal is that I made myself a kydex holster.
The contact points are tight for retention. Especially at the trigger guard. I made a sight channel in the holster, but my tolerences werent that good. So, the top left of the front sight was lightly scraping on the inside of the holster.
Just after 10 draws, the top lefthand of the sight got rough and has some plastic shaved off of it.
I fixed my sight channel, and have drawn and reholstered MANY times.
The polymer of the frame doesn't show any signs of wear from the rubbing and snapping of the kydex.
So, I guess I should have said I don't know why the make them of softer plastic.