Since the NES days at least companies have striven to create characters they could milk into a franchise. On popular platforms this usually meant level editor quality sequels with the same exact gameplay plus a few things. More innovative companies might take the same characters and try them in a totally different genre (or new genre), but that rarely, or never, resulted in a cash cow.
I think the whole Mascot thing was just bragging rights for Nintendo fans while they waited for the Super Nintendo and sort of window shopped at the Genesis. Sega had dozens of characters that more than filled that void in gameplay quality, but none of them had the entire gaming media hype their first game as some sort of system selling AAA title.
This is exactly what happened with Grand Theft Auto III and Halo, and Mario/Zelda64, or even Street Fighter II World Warrior and Turbo on SNES (Mario World failed to propel the SNES in the same way).
More recently the biggest nastiest cash cows tend to be multiplatform but are still obvious cookie cutter same genre franchises plus extras. If a system flounders in sales the company responsible will attempt to make a super wiz bang "AAA", and if they succeed they will milk it for all it is worth.