Yes, it's a pity astroid belts don't do anything, more so because scanning them takes a lot of time. Maybe it's an idea to put an extra 'bonus' in for detail scanning the whole system including the belts. And after that, make it available for everyone, so you can see what's completely scanned. This way it's far more realistic and you also help those people who don't do exploring so they (and you) don't jumping in unscanned systems (some of which have been (partially) scanned over and over again before) all the time...
The way it's now you are just mapping for yourself only and in the long run that's less fun and less mmo. For those complaining you take away a way of earning money, most undiscovered systems within occupied space are still not fully detail scanned, so with this in place you could still earn the bonus for a complete scan. Besides that, with 400 biljoen stars there should be enough to discover for those who want their name tag there for tens of thousends of years... And is it not in the far reaches of the galaxy where the real explorers wander?