Actually, the reason I was trying to avoid the drywall was simply that
I have no experience in putting it up. I figured the insulation
couldn't be too hard, but the drywall I could screw up.

From all the threads, I'm still not sure if there's a specific thermal
or security reason to put up the drywall... Everyone seems to agree
that I should, which I probably will, but is there a building code rule
of some sort around it or does it make a difference in terms of
temperature inside the garage with/without the drywall?