I wrote a little something on female characters in early NES games.
The gist: If you think old school Nintendo was all female characters locked in dungeons, you’re wrong: The Mother Brain is a female big bad, in a few different ways, and that’s one of the quirks that makes Metroid and Kid Icarus a hell of a lot more progressive, gender-wise, than old-school Super Mario Bros. and Legend of Zelda were.
Surprising discovery for me from this article — I’ve always considered Metroid a successful franchise. But, I guess you’re right. There was only one game for the NES. One for Gameboy. One for the SNES (The best Metroid game by far, and maybe one of the top 5 video games of all time). By that point, Mario had countless sequels and spin-offs. There was no Samus Paint.
That said, I feel like Metroid was a part of the Nintendo culture, if not supported with actual games. It was part of Captain N. It got the cover of Nintendo Power several times.
I dunno, I feel it’s walking a line to say it wasn’t successful until 2002. But, I’m going on anecdotes and you’re well-researched so I’ll shut up about it.