I can give some obvious drawbacks. For instance, flights where you aren't in an exit or bulkhead row are insane, and not just for you, but for the person in front of you. The last time I wasn't able to get a good seat the guy in front ended up switching with me. Sure, he was a nice guy, but quite literally the force of my knees on his seat was tilting him, and any time I adjusted (because I was in pain, for crying out loud) it meant a severe jostling.
