Thrash metal was a bit before their time but their contributions helped get us there. The Kiss look was pure propaganda to generate cash. Gene Simmons was/is a marketing whore. Research all the early Kiss swag. They were way ahead of their time in that regard.
I grew up in that era but living in Europe at the time I was never into them and to this day never bought or owned a Kiss album despite having a collection of R&R of over 2000 albums. The Grateful Dead escaped my interest as well.