SEGA may not take the comments seriously, but they for sure don't go unnoticed. The community team knows all too well that the demand for Shenmue is a big one. So, while the suits may not see the comments, the feedback online is passed up through the chain of command, or at least that's what the community team says.
As for Shenmue Gai, I think Yu wants to finish the story as badly, if not worse than the fans want a third game. He created his own studio, and their first project is Shenmue. That isn't fan service, that's a man wanting to see his project through, no matter how many baby steps he has to take to achieve his goal.