Allowing people to recline (it's only a few inches anyway) on a domestic flight is totally the problem. If reclining is possible, people will do it. I never recline unless the person in front of me reclines, and starts the domino effect all the way to the end of the plane. The airlines need to disengage the reclining mechanism and the problem would go away.
Everyone who has the Knee Defender probably hated the fact that it became a public issue last week. I'm sure most people that used them hoped that the passenger in front of them thought their seat recline didn't work. Now the secret is out. Why should you, as a passenger, have any control over the seat in front of you?