Just because they don't acknowledge every bug on the forum doesn't mean they don't read the reports, as S397 have themselves mentioned. A lot of time from actual work will be taken away by fully addressing all community concerns. Rather than offering speculative answers about when bug X or feature X is addressed, it's more important IMO to just get them addressed. The roadmaps are also increasingly criticized and some people even confuse roadmaps for actual game updates. It's just a piece of text, now it seems people determine the fate of rF2 through some roadmap article somebody probably quickly wrote together

.
I agree some people associate roadmaps with build updates etc, though I don't know if the roadmaps are responsible for that or able to help counter it.
As far as giving information in the roadmap, I see two reason to give slightly more detailed information about what's currently being looked at, reviewed, and planned for the future: 1. existing players, aware of the various issues, can 'see' some progress or at least some planning being done, instead of silence. 2. potential new players (or newly new players, if I can mangle my english) have a better understanding of where the game's at (which, realistically, is WIP phase) rather than seeing only bright bubbly roadmaps talking about competitions, past events, and upcoming content and being unpleasantly surprised when they buy the game and find some features aren't fully fleshed out or working properly.
I have to say I think the roadmap can be both marketing and development. It doesn't need to be all grind, no one wants that really.
Oh, and that 'extra info' just needs to be like Marrs posted earlier in this thread, maybe half a quick rundown on what they're planning and half addressing common recent questions/complaints. Some people seem to think buying a game gives them a right to dictate how it's developed, or even make demands on content etc. It's just a game, so if you need more than high level information either make your own game or work your way onto the rF2 team and discuss it properly.