The only reason he doesn't is because an NFL rule prohibits owners from coaching. That's why Al Davis stopped coaching, even though he regularly interferes with the head coach's decisions.
Jerry Jones is a younger Al Davis. The good news for Raiders fans is that Al Davis will die soon. The bad news for Cowboys fans is that Jerry Jones' ego won't allow him to sell the team until it wins a Super Bowl under his watch; meanwhile, the team is guaranteed to not win a Super Bowl under his watch.
Jerry Jones is an ass and has been since day one. At least his management and football skills are slightly better than the utterly incompetent Daniel Snyder.
Clint Murchison didn't pretend to know how to run or field a team - but he hired people who did.