Sonic 4 however has no such luxury with me. It breaks the natural flow the numbered sequels had going on by doing blatant callbacks. Sure some of the levels between games shared themes sometimes, but it never never felt like it was largely ripping off a previous level (Scrapbrain Act 3 excluded). For example, I can see some similarities between Flying Battery and Metropolis but I never feel like I'm playing the same level between the two. But Casino Street feels like an extension of Casino Night with shitty physics.
But like I said, other than re-releases, Sonic 4, and Sonic Generations, I can't seem to recall the nostalgia card being played that much over the past ten years. Heroes, Shadow, 0shit, Unleashed, Secret Rings, Black Night, or Colors don't have anything that screams to me that the nostalgia card was being played very much. It seems that it is just between two recent games and one of them does have no business playing the nostalgia card.
And on the discussion about a reboot; no. Instead of a reboot I'd rather see them take advantage of the space in-between Sonic 1 and 2 and create a side-series from that. Have the team that made Colors be behind it and then have the team that worked on Generations continue on with Modern Sonic. I figure since they already brought Classic Sonic back that they might as well do this. A man can dream, amirite?