Gah, I read about that ^^ fiasco. People are absurd.
The Knee Defender device is obnoxious.. I'm glad it's banned on most US airlines. Stuff like that makes my blood boil a bit. I'd demand the other passenger pay for my seat if he's gonna limit my use of it. Obviously that's not enforceable, though. Personally, I can't sit pin straight for hours on end because it causes pain where I previously fractured my spine- leaning backward even just a little takes the pressure off the area. I'd be pretty livid if someone kept me from being able to use the seat's reclining feature. I'm tall; I understand that no legroom is a bitch, but you can get a seat upgrade at a deeply discounted rate at the last minute on some flights, if you want more leg room. Or, take a bulkhead seat. Seatguru.com is a handy site to quickly research/compare which airlines/aircraft have the best recline &/or legroom for every class. Sheesh. Plan a little. Worst case scenario, you might be able to be reseated once you're airborne- not all flights are fully booked in coach, & most flight attendants can be pretty accommodating if you don't treat them like crap.
Ultimately, you buy your seat knowing (or having the ability to access that info) how much leg room you'll have, and knowing full well that the seats have a reclining feature. I dunno what makes people think they're entitled to basically rob others of what they too, have paid for.