Companies eventually iron out their MIM issues.
Ruger had some issues with a batch of front sights, but that was 2 years ago; it was pretty clear that it was a bad batch because most mentions of the problem on-line came within a month of each other, then we heard no more about it.
Colt too had problems in the past, but those are nearly two decades old. S&W had some broken slidestops at one point, then no more complaints, either. Kimber seems to be getting very few complaints lately, too.
There will probably come a time, not too far in the future, when complaining about MIM parts will begin to look silly. We're not complaining about the MIM blades in commercial jet engines, are we?
Too many people miss the silver lining because they're expecting gold.