Well just like anything they balance our ecosystem sometimes in a way we cannot understand. If they were like feral hogs than I would say they aren't good for much. BUT, for the most part bears are not invasive. The population increase, if not managed by hunting, would eventually level out and cause a die off just like how rabbits, bobcats and coyotes have population booms and die offs.
I myself enjoy seeing, hunting and eating bear. It's something I was raised doing just like hunting whitetail. They aren't much a nuisance here besides in town dumps. For the most part they leave crops alone up here and chow on the plentiful blueberry and raspberry crop we have every year. People rarely see them outside of hunting conditions and we have a very healthy bear population. Black ghosts they are... I get the farmer frustration standpoint though!