I was doing some reading and I think I've got a handle on why everyone seems to hate Sonic... well, everyone as in most 30 year old dudes found scattered across various internet forums.
The theory is these people were mostly taken with the theatrics of old-school Sonic titles, you know, the part where Sonic just goes flying across the screen and you don't really have to do anything? Well, they really liked that as a kid. Then when Sega tried to introduce more substance into Sonic games, it didn't have the same effect. Compound that will numerous entries (some buggy and some polished) that didn't make the same kind of magic happen, they got really annoyed with the franchise. They demanded old Sonic back and then when they were given old Sonic, they realized as adults that this doesn't entertain them anymore.
Only problem is they continue to think this is Sega's fault. Like if Sega would just somehow do better then they'd love the game again? What worked as a tech demo 30 years ago, is not enough for a whole game by today's standards and yet folks were never very accepting of the franchise moving in a different direction, the shunning began first with Sonic 3D Blast and snowballed from there.
My thought is if Sonic doesn't do it for you, then so what. Doesn't mean all the games suck. Sometimes your preference of game changes, it happens.