Maintain your guns better. I have no clue how a self respecting gun owner gets rust on his guns. It takes less than an hour to disassemble and clean a gun after each use. All guns have the potential to break or wear. Using your example of one or two guns does not mean their production is shitty. I've never once heard the phrase about Kel-Tec that you mentioned earlier and I know a lot of guys that own them.
The rust occurred because the metal finish was inconsistent and missing in places.
How could I have prevented the polymer from cracking? Not like I abused the gun or anything. If anything I babied it because it was my carry piece for awhile.
Use what you like, but Kel Tecs QC issues aren't exactly a secret. If yours are proven reliable and you trust them with your life then good for you. Mine weren't, and I didn't trust them so they got replaced.