I have absolutely NO intention of flaming anyone here, but isn't SIA's pitch also 32"? Why isn't it, say, 36"?
Profit matters, because airlines are not non-profit organisations. They have employees, the employees' families, and (maybe to a lesser extent) the shareholders.
We can always argue that there's a middle ground, that instead of going to the extremes there's a way to make every situation win-win. But that's not always true, and when it's true people don't always manage to achieve that.
I think that's the reason. Even though you can argue that 2" extra doesn't take out too many seats, it may amount to the difference between 2 members of the same airliner family.
Of course, there's also a less important issue. The average height of people also grows over time. Maybe 31-32" was enough a while ago. People are not all of the same proportion, either.
I'm 5'7" (1.7m); my mom is definitely less than 1.6m (5'3"). About 10 years ago she flew on CX, and found it too cramped even for her. Needless to say, she's never chosen CX since (although I probably could, that BBC world service thing is really attractive).
On second thought, I'm quite used to 38" pitch now, and can't quite imagine anything below 34". It's not that there's no space for my legs. it's that when everyone lays back and sleep, the seat back in front really eats into your available space. It's trying to move past the people next to you, so you can walk around, go to the lav, etc.
Someone tell me how many have died/been hospitalized on DVT from flying charter. I think so many people are, for a variety of reasons, not taking enough care of themselves. Maybe the condition of the cabin inflight just aggravates all the problems you've got that haven't really surfaced.
I have heard of deaths after 3,4 years of fast food (as a major part of one's diet); cancer of the lymph nodes, I think.