Also, these cabs are for home use. Remember, companies like Nintendo used smoke plexi for their actual machines.
My personal preference -- when I have the choice -- is glass. Nothing looks better. Having said that, plexi is fine and cheaper... right up until it is scratched. Then it is ---steaming pile of meadow muffin---. But then again, tempering is expensive and if you've ever set a sheet of tempered glass down wrong, even more expensive.
Properly cared for (as you say, home use ... just clean it properly), and in a configuration that doesn't leave it prone to scratched, plexi is fine. I have two Atari cabs (dating from 1976 and 1979), both with original plexi that still look great. And my Ninty, while not really a poster boy for quality cab construction, still has original smoked plexi and looks fine.
EDIT: I wasn't clear about the plexi on my old cabs -- all of them were in-arcade and then on-route machines and the plexi is still nice.