There is nothing in windows that’s a small tweak.
Changing anything has implications to a banking business Joe somewhere, who’s program depends on the original feature working as it does, or one of the 16 layers of code is simply tangled in a way such change would require cascade of rewrites.
I’ve read articles about various developments: working with regex registry*, or just adding a control panel option, and it’s an absolute nightmare.





Metal doesn’t generaly cause issues in the microwave unless there are sharp corners.
The whole inside of the microwave is metal (*you will notice curves and round corners everywhere, as well as surfaces made to specific angles).
It does reflect the waves, however, which can mess with the heating distribution.