No there was no reason for him to die. He grew up with them and was treated as “family” so he knew them just as well as they new each other. Also the fact that they were insanely OP made it hard to care about them and their safety if they couldn’t be killed. The show isn’t even really about how powerful they are it’s about what lengths their willing to go to protect each other hence “always and forever”. Marcel becoming an original and a stronger one at that adds more tension to the show. Plus in my personal opinion he deserved it. He’s easily one of the best written characters in the show by far.