The high stakes world of video games writing is a very strange place sometimes...
A lot of people want video games to be taken seriously as a medium, and somehow that involves revising the 'canon' and sweeping older games under the rug. It might be a trite thing to say but you don't see people dismiss films like say, The Great Train Robbery or Broken Blossoms, without commending their contributions to cinema as a whole. We can also say that they are 'good' films from the Silent Era from a direction, performance etc. point of view.
Not much has changed since the first Sonic games, games are still sold on the back of their technical muscle and they still function in mostly the same manner. It's perfectly fine to not enjoy something in this day-and-age but it's another to say that something was never good at all, there are plenty of games from that era that were never good (Bubsy) but Sonic ain't one of 'em.