I think part of why a lot of people are turning against games like Colors and Generations more and more is because of the current state of the series in general. Instead of improving upon what those games built up with their gameplay, they went backwards and started downgrading everything, and when people start noticing all these glaring issues in Lost World and Forces, they start noticing it more in Colors and Generations. Had Sonic Team followed up with some quality games with more interesting stories (the writing for the games doesn't have to be a mind-blowing masterpiece or anything, just something on par with at least the Adventure games or even the Storybook games), and had started allowing more characters playable other than just Sonic and alternate universe Classic Sonic in the mainline games again, maybe things would be different. At the very least, the folks who didn't like those games could just shrug them off and say, 'well Colors was a little breather game after the dark ages for the Wii, and Generations was just celebrating the 20th Anniversary', and let them slide, but no, that's not what happened. The 3D games we've been getting post-Generations have been painfully mediocre, and many of the issues people have with those games seem to have stemmed from Colors, Generations, and to an extent, Unleashed. Hell we've had the same FINAL BOSS 3 times in a row, and that boss originated from Colors. So when you put it into perspective, it's not really all that surprising to me that people are turning against the game. Morio Kishimoto is a bad director for this series, and I think it's time for him to step down. Another factor is that there's less games coming out to distract the fans on top of that; so they have more time to stop and analyze all the issues they have with the series, and unrest is building up in the midst of the news drought and the looming fear of another disappointment from Sonic Team, which in turn is making the fanbase split off into even more factions, and are becoming more at each other's throats again over social media as a result. SEGA's dug the franchise into this weird hole with how poorly they've handled the series over the past 20 years or so, and now this split fanbase is the result.