In all honesty, a roadmap would be a great "feature" for Blesta to have when prospecting for new license sales. It would certainly allow people like me to make a more informed decision on whether we want to use Blesta or some other billing system.
If I know that needed "feature x" and "feature y" are in the queue (and what order in the queue), then I'm much more likely to consider Blesta.
Furthermore, I would argue there are few features so secret they can't be added to a public roadmap. Of course, if there's some radical new feature that no other billing system has, then it could be left out. However, I see no reason why any feature that exists in other billing systems shouldn't be included in a public roadmap. It would only serve to show Blesta management is serious and knowledgeable about the direction of their software, in order to make it fully competitive with the others available.
Thanks.