It's a fine balance and not everyone is going to agree with. What some people see as "better" gameplay, others will just simply disagree. Sonic Colours gameplay was seen as better than Generations, but I do not like Sonic Colours much at all, granted I do not like the boost gameplay much either.
But what we have seen is that the boost gameplay, as bad as it has been for some, has done well to get Sonic back into the limelight for others. Not everyone is going to accept it, or may just think its a terrible gimmick altogether, but there is no denying that there are people that do like it.
I mean look at Phantasy Star Online 2, some people dislike where that game has gone whilst others are very much enjoying the title, so even if you try something new, it might not resonate with all fans and that is what happens with long running series. Even being a big Yakuza fan, I am not a fan of the PSP spinoff, even if it does contain all the ingredients to make it the best in the series (And to quite a few fans, it is) but it is just too different for me to like, whilst the more refined Yakuza 5 is my favourite in the series and probably my favourite game of all time now.
Back to Sonic, the series should be reinvented when the time comes and not before, so far the boost gameplay is yet to fall out with fans outside of the classic fans (I'm in that group) but take yourself back from what you perceive at being for the best and what is working currently or being enjoyed now rather.