While it's annoying from a traditionalist view, the plastic 10/22 trigger housing actually is a better quality part than the older alloy ones.
Ruger switched because aluminum is more abrasive to the casting molds than polymer. Those were cast in gang molds, with multiple cavities. The cavities wore unevenly, which was leaving molds with one or two cavities that were worn out while the others were still usable. Since molds are not cheap, it wasn't economically feasible to toss one out when just one cavity might be unusable, so Ruger would continue to use the mold till other cavities wore out, but obviously at reduced capacity since the bad cavity couldn't be filled on each pour along with the good ones that could.
That was inefficient from a manufacturing process, and negatively affected Ruger.
The part that negatively affected us, the buyers, was that as molds began to wear at different rates, the quality of the castings from a given mold was variable. Those used on production guns had to remain within certain tolerance ranges, but edges might be a little less squared on some, overall dimensions might be a tiny fraction larger on some, pinholes might be a little less precise on some, and so on.
That sometimes resulted in what you could probably consider a "sloppier" overall fit. Which is NOT saying such guns were sloppy in themselves or shoddily made.
It also sometimes meant more time might be needed by an assembler on some guns in correcting very minor imperfections.
The 10/22 was designed to be a mass-produced item, and each time one or more guns requires more individual attention than others it slows down the production process.
Polymer wears the molds at a more even and slower rate, which allows Ruger to continue using them at full-pour-capacity longer, and it also produces more uniform trigger housings with more uniform pinholes & other critical dimensions.
Polymer housings are also much stronger than aluminum counterparts. A drop on an alloy housing will either bend it or break it entirely, an equivalent drop on a polymer housing may scratch or nick it, but won't otherwise harm it.
I'm a traditionalist myself, but I have to admit I can see the sense of the change in materials here.
It actually does benefit both Ruger AND the consumer.
Denis