Think of it this way. It's Sonic, therefore it's our right as loyal fans to complain!
There's a major difference between legitimate complaints and what the vast majority of the Sonic "Fanbase" does. I'm not sure if you remember, but back when Sonic 4, Episode 1 was announced, people complained not only by the fact that in the trailer, Sonic had no running animation, but also for the fact that he simply was Modern Sonic instead of Classic Sonic,
completely ignoring the fact that for some unexplained reason, Sonic became Modern Sonic in Sonic Adventure 2, just because the game was named Sonic 4.
Now, I would like to say that Sonic 4, Episode 2 isn't a bad game by any stretch of the imagination, I've played it both in single player and co-op and I would like to say that I do think that I did get my money's worth with buying this game. Now is it the best Sonic game in the franchise? No, not really, since it does have some problems, notably the lack of difficulty through a first run. I mean the only trouble I had was Special Stage 7, which wasn't really challenging, just more cheap, because the game outright made it so that you had to rely on the AI to collect the bonus rings if you didn't have enough(470+) rings before you hit the second checkpoint. As for the bosses, I don't feel that they are dragged out at all, if you're finding their length a problem, just use Super Sonic, which by the way does double damage to any enemy, including bosses(Except for Metal Sonic in Sky Fortress Act 1, but then again you're not directly attacking him).
Bottomless pits and auto-running are fine in 3D games because of the enhanced movement and camera position, but in 2D games they're just NO GOOD.
I would like to point out that bottomless pits have been a staple of the Platforming Genre since the first Super Mario Brothers and have appeared so far in every 2D Platformer(One was at the end of Sonic CD) within the Sonic Series.