Antimicrobial treatment helps prevent bacterial growth and odor in your hip protectors, which can be especially handy on multi-day ski trips where washing isn't practical. The treatment keeps things fresher longer, so you're not stuck with funky-smelling pads by day three of a ski week.
That said, antimicrobial treatment is a nice-to-have, not a must-have. If you're mostly doing day trips and can wash your protectors after each use, there's no need to pay extra for this feature. Most quality hip protectors include some form of odor control anyway.
Just remember: antimicrobial doesn't mean self-cleaning. You still need to wash your protectors regularly—skipping washes because they're 'antimicrobial' is a common mistake that can lead to skin irritation and degraded padding over time.