Yeah there probably aren't too many people who really care about Snake Plissken as a character, but if there's any drive to make him the next guest, it's mostly around love for Kurt Russell himself. I think it's fair to say he has at least as much 80s and 90s pop culture cachet as Arnold and Stallone, only more across all his roles rather than 1-2 signature ones. Plissken isn't all that iconic a character, but comes to mind because he's the best fit for an MK game. My guess tho is that if NRS is even considering him (who knows?), they won't bother unless they can get Russell himself to do the voice acting.
Also--just imo, but I don't see how Robocop is bottom of the barrel. The first two movies (only ones worth watching) are dark, violent, absolute cult classics. The character had a pretty big impact on pop culture and is super nostalgic. We can argue about how well a clunky, slow, gun-slinging cyborg fits in a FG (I think his design is fine, but I get why a lot of people don't), but he definitely fits thematically as a guest.
