Considering Chester's stated several times that he doesn't intend DBS to be a one-time-only thing, if they're going to make more music somewhere down the line, why wouldn't he want to know what they could do better the next time around? Obviously he believes in the music he made with this album, and a lot of people seem to like it, so that doesn't really explain why DBS wasn't very successful commercially. There are other areas that need to be improved on if DBS is ever going to amount to anything significant, and fan feedback is a good way to find out what needs to be addressed.
You can bet that if DBS makes another album, Chester's going to revamp their management team significantly and focus on doing better promotion. The number of people who have mentioned DBS's lack of promotion isn't going to be ignored.