Oh please, even in the 90s Sonic had so much crap going on, so much spin-off and cartoons and comics.
Sonic was always the Sega's milking cow since the beginning.
It was probably worse in that regard, with "alternative universes", multiple canons...
And that didn't hurt the main Mega Drive titles in the long run overall, in fact are the most cherished titles out there
But no one really knew too much about the titles otehr than Sonic, Sonic 2, Sonic 3, Sonic and Knuckles, Sonic Spinball and Sonic 3D Blast. Seriously, anyone who played the Game Gear games at the time was lucky to play them, especially in the UK. Most people I knew hadn't even played Sonic CD, and I was the only one in my primary school to do so. I didn't know (and still don't know) anyone who owned a Game Gear. Sonic games averaged at about every year and half, which was hardly saturated. Yeah, you had the cartoons and the comics and such which complicated matters, but those were nothing to do with the games themselves. From 1991 to 1996 you had about 8 well known Sonic games.
From 2005 to 2011 we've had Shadow The Hedgehog, Sonic Rush, Sonic Riders, Sonic The Hedgehog 2006, Sonic and The Secret Rings, Sonic Rivals, Sonic Riders; Zero Gravity, Sonic Rush Adventure, Sonic Rivals 2, Sonic Unleashed, Sonic Free Riders, Chronicles, Sonic and The Black Knight, Sonic 4; Episode I, Sonic Colours on both Wii and DS and now Sonic Generations, not to mention the re-releases, All Stars and Olympic games. Pretty much all of these games have been pretty well known to gamers this generation. Hopefully they'll tone it down a little bit in future, after they release the next storybook game.