It always bothered me how classic Tails (who is quite clearly younger than classic Sonic) in Generations was able to speak, and so was classic Eggman...but not classic Sonic himself. I'm not taking the "voice for the voiceless" thing, because I don't remember one scene in which classic Tails spoke on classic Sonic's behalf at all. :/
What I find even more stupid is that Sega decided to keep classic sonic mute because "that's the way he was in the genesis games". The hell? Tails and Eggy couldn't speak in the genesis games either yet they are perfectly capable of speaking in generations. Something's telling me Sega must have caved in to the fanbase on this one.