I don't get it when people are assholes to each other like this instead of just communicating. If I want to recline my seat on a plane and there's a person behind me, I ask them "Do you mind if I recline my seat?" If someone in front of me reclines without asking, having quite long legs and almost always getting squashed by this, I ask them "Sorry, would you mind putting your seat back upright? I don't have much space for my legs". Doing this, nobody has ever declined me. Everybody's happy.

I've heard one or two stories about people being rudely declined in situations like that, and in those cases they've asked their flight attendants to switch seats because of this (and in one case I remember, got bumped up to first class).