Honestly if I was to put a metroidvania on steam right now I'd call it an Exploration Platformer or an Action-Exploration Platformer
Seriously though, can Exploration [Game] not be a genre name for some reason? We have Racing and Fighting and Platforming, why is Exploring something that doesn't make sense to people? It's not that vague really.
I guess the genre boom came after Metroidvania was coined, so...