I'm sorry, but this whole bitching and moaning thing about game mechanics is lame, let me explain:
First off, I highly doubt a Sonic title will ever go back to it's roots or be as good as the original Genesis titles simply due to the fact that the games themselves are being developed by a decimated Sonic Team that is only that in name. The minds behind the programming are no longer there, so you can't expect a game developed by inferior minds to be near as good. Also, this mantra about the 3-D games not being as good is rather hindered by the 3-D environments themselves. It's really hard to design a roller coaster level of the magnitude of Sonic 1-3-Knuckles because it involves about 10 times the amount of programming a sidescroller does. Sonic will never reach that amount of potential it had back in the old days again because the programmers insist on putting out half-ass efforts that aren't satisfying to those of us who actually have played alot of the older games. I wasn't even a fan of Sonic until just recently when I bought my Genesis and the first four Sonic games, as a kid, I found the games too fast to follow and unbeatable. Now I find them refreshing and fun compared to the older Nintendo titles. The fact of the matter is, it's hard to go back to a game's true roots without having the original development team to pour their minds into it. Point in fact.
Sure you could suggest that they go with Capcom's idea and restore the game to it's original programming and expand upon it like MM9 and 10, or hire fresh developers to remake a classic, as Nintendo did hiring Retro Studios to make DKCR, but the fact of the matter is: Sega doesn't want to make the effort to make Sonic new and fun again, they insist on milking the population of fans until the franchise is as old, dry and boring as Mario is getting these days.
At least Sega isn't remaking the same game over and over again and calling it new (Zelda anyone?)