That’s a fair point about the SNK game’s legacy. Maybe they can be seen as equals? SNK influenced more, but Tekken was more popular?
I think the lack of Mario inspired indie games is because 2D Mario is as basic as it gets, as well as everyone & their mother having played atleast one. There’s a lot more room for interesting stuff with the Mega Man & Metroid styles. I’m surprised there’s not more Sonic style indie games.
I think in the case of Sonic, you mostly have fans making Sonic fan games, rather than indie titles inspired by it. Though there is Freedom Planet and Spark the Electric Jester. Both of those I think are getting at least one other game. Not to mention, Sonic was a big contributing factor to "Scrimblos" like Bubsy, Awesome Possum, and the actually successful Crash, as they wanted strike lightning twice, so to speak.
And I think the lack of Tekken-like games, which also extends to VF, is that 3D fighting games aren't the in thing right now. Not like they were in the PS1/N64/Saturn and PS2/XBox/Gamecube/Dreamcast days.