Dealing with passengers is our proper responsibility. The life support systems ("It's too hot"/"It's too cold") are our responsibility. Cabin pressurization, passenger comfort regarding turbulence, etc... All that is under the purview of the pilots. And under federal law, a captain is a peace officer and has ultimate authority and responsibility for his aircraft and its occupants. There's also never just one of us assigned to fly it, and both of us would never leave the cockpit at the same time. We're not idiots.
If I get called out, it's because things are bad. As in yelling and cursing bad. And I just treat people like children since they're behaving like them. Get along or I'm turning this thing around and going home. And in the case of a dispute over a reclined seat, I usually tell the FAs (if they ask) or the passengers (if I get called out) to put their seatbacks upright. I manage to get by without reclining my seat, it's not that big a deal. Don't like it? You're welcome to be placed under arrest by me and meet the RCMP, FBI, Polizei, Carabinieri, etc when we land.
Pilots can say whatever they want, the law says thou shalt obey the rules of thy cabin crew. So the airlines won't change it our whims and potential lost income just because we say we have to go back every now and then. And the number of times I'm called back to deal with disputes is minimal. On the whole, people are reasonable creatures. It's not like I spend 90% of my time in the back dealing with complaints. Besides, be careful what you ask for. The result of claiming insufficient legroom causes reclining seats to create unsafe situations wouldn't be more legroom, it would be seats that can't recline.
The only secret to upgrades is ask. Some staff are annoyed by people that ask, but you won't be upgraded be being silent either. If you ask and you're told no, you're up shit creek. My only useful advice would be...become a pilot or a flight attendant or a mechanic, and start travelling on flight benefits.