It's a business decision for each individual airline. Most recently, US Airways started putting changing tables in the bathrooms of all its new Airbus aircraft. I already hate the discomfort of flying so much, I only fly if I have to. Actually, I would have to disagree that airlines show no concern for comfort or safety. On the comfort side, airlines constantly have to juggle economics and comfort.
Most airlines are in the process of upgrading all classes of service trying to improve comfort.
Actually, pitch varies not only from airline to airline, but from airplane to airplane within an airline's fleet. As I mentioned, pitch is a business decision for each airline. The challenge that all airlines face is getting the most revenue for the space they have. While cramped seating undoubtedly plays a role, I think that there are a lot more factors that go into the rise in air rage statistics, including alcohol, fuller planes, tighter carry-on restrictions, etc. It's tough to pin down and quantify.