Yes, the long trial lengths are also a problem, and maybe an easier one to fix, by adding expedited hearings just for these things. But at the end of the day the trolls troll because the reward is greater than the risk.
Second, there is no legal theory or precedent that I’m aware of that would factor in the troll-ish nature of the plaintiff in a patent ruling. Patent trolls lose because they are usually stretching to apply vague patent claims to a large number of targets.
Finally, trolls have a heavily uneven playing field. Most troll farms have in-house counsel, so they have very low litigation costs. Also, they typically segregate every patent or patent family into a separate corporate entity so that any fee or damage awards won’t claw back overall winnings.