By your standards "Nothing justifies denying someone access to something they legally paid for.." so you're contradicting yourself. Which is it? Is it OK to do things out of the courtesy of decent people or is it an entitled right once paid for? I understand the knee defender because that is kind of a dick move in the beginning and also a slippery slope. Having to do with compensation though, how to you compensate someone for lost time with loved ones or other travel plans that get messed up like connecting flights or anything time sensitive? They have the right to demand but sometimes that shit isn't possible. Now circling back to what the core of the issue is here, just as the person in front of OP wasn't obliged to move his seat, OP had no obligation what so ever to be comfortable in one position the whole flight. Maybe he just wanted to move around? It was his "right" to do whatever he damn well pleased with that seat, and no one should be able to judge him in terms of basic action if you think the original guy in front had done nothing wrong.