They always seemed like the epitome of commercial music to me, they just felt like a merchandise brand with a band included in the package
If their music sucked then they wouldn't have two dozen gold albums, albums don't come with a show or a gimmick, it's just music, and they sold a carp ton of it. Plus, most who say stuff like that about KISS have never put on an album. Ace Frehley inspired countless to pick up the guitar. In the 80's KISS took off the make-up to prove they weren't a gimmick, every album KISS did after that went gold, along with all their tours selling out. Trust me, the gimmick would have worn out fast if their music sucked, put on the self-titled, that laid the groundwork for metal and rock to come.