It's really simple. If the airlines didn't want people to be able to recline their seats, they wouldn't give people the option. If you are unusually large and way bigger than the normal person, it's not the person's job in front of you to subsidize your comfort at the cost of theirs ... just so you don't have to pony up money for a seat with more leg room.
It's all about who should have to deal with the inconvenience that comes with being abnormally tall. Should the person who has the condition have to deal with it or should other people have to deal with it.
These people who whine about it are cut from the same cloth as people who are hypersensitive to smells and cologne and who feel that their problem is actually not theirs at all, but really the problem of everyone else, who should be expected to live their lives as if the person with the hypersensitivity is the center of the universe.