My opinion is that reclining seats in Coach are an anachronism left over from the days that there was actually adequate seat pitch in coach. On airlines (like AA) with MRTC (on SOME planes) or (like UA) with E+ seating (for SOME coach seats), I suspect that reclining coach seats are just fine, but once seat pitch has been diminished to 30" - 31", reclining your coach seat becomes a problem for the passenger behind you.