Of course it is all about money and fuel but I think they do care about comfort as if a person is not comfortable they will find a new airline.
Bottom line, if they can charge more they will. Weren't they charging for extra bags or something too or meals, can't remember right now what all they were doing.
My question with all of this is how do they determine what is over weight. Would everyone be weighed upon check in if not it is prejudiced.