dat track is sum gud sht fam
Well technically, they not necessarily wrong. There are different audiences regarding 2D games and 3D games. You can see this on the Wii with NSMBW massively outselling both Galaxy games; though the sales of NSMB and Super Mario 3D titles on the 3DS and Wii U are roughly on par with each other. (3D Sonic games themselves also have a split inof themselves with people who like "traditional" platformers like Adventure and Lost World and people who like the boost games like Unleashed and Generations, but that's a different story.)
I'd say the real problem with Sonic Team's attitudes towards the audience for Sonic games is that they believe people who like 2D games and 3D games are segregated by age groups; what not with how they've called Sonic 4 and Mania both being "for older fans" and Colors and Forces being "for younger fans" (ironic, that, given how both titles they seem to be heavily compromised of 2D gameplay). Age groups are irrelevant to quality game design; if a game is good, older fans and newer fans will gravitate towards it just the same.