The system the players have been playing under has been highly successful and made the players richer than they ever were before. So basically it ALL does come down to them and their greedy agents. But with their greed potentially comes a last capped season, an uncapped season in which fewer players become UFA's and they lose their pensions, and then they face a lockout in which they'd make NO money. Stupid is as stupid does, and I guess they didn't learn their lesson from the NHL.
But you're right that the owners have some fault. It was the greedy ones who gave-in immediately to the NFLPA's demands for more money, because they figured that with a cap based on ALL revenue, but without ALL revenue being shared, they'd have an edge over the less-successful franchises. And once you gave into that, the NFLPA was never going to give that up. But with a potential stoppage of play in 2008, those large market teams with their overextended debt are going to be hurting BIG TIME.