I don't recline as I always feel guilty, although if the seat mechanism allows it then I can't question anyone else who wants to. I resolve this to my entire satisfaction by booking exit row seats if not in WTP or CW, so that feels like a win-win for me and the person behind me. I do feel sorry for those in middle seats in WT though when the passenger in front of them fully reclines. With the cabin densification, that seat has a shockingly small amount of space either in terms of arm-room or knee space.

Once though I had a really angry person in front of me in ET when I was in the exit row. He pressed the cabin bell to get a crew member and he said, in a rather loud tone, that "the customer behind is blocking my seat recline with his knees". I'm fairly sure that his seat didn't have a button to press to recline, as he just seemed to be trying to get the seat to recline by barging back on it hard, which produced some interesting theatre for me. The crew member informed him that on that aircraft the seat was designed not to recline into an exit row for safety reasons, and he remained most put out. He turned round and glared at me and I hope that my helpful smile made him feel better....