It's not a problem, it's a feature
I sand the top of the pad printed keycaps, to make them GMK blanks, it works out well, when you finish with 2000+ grit - It looks shiny, yet it has a strong invisible grip, unlike the naturally shined keycaps
I don't see any point in doing this for all the keycaps tho
Maybe if you have shined keycaps, and you want something new, you could do this, get to re-wear them later-on, would probably take 2-3 months