Well, we/they can't have everything! We/they get what we/they pay for.
Want extra legroom? Pay for premium economy or business (or better still, first) class.
Want comfort but don't want to pay extra for it? Staying in our lounge room would be perfectly comfortable.
When I really didn't feel like being cramped up, I coughed up for business class. Most times, I put up with economy class seats because I don't want to pay a fortune just to go from A to B. I can cope with temporary discomfort to save some $$$. If I find that far too uncomfortable, then perhaps, I shouldn't be flying. Harsh? Yes. Who said the world is a fair place, anyway?
And one could argue that increasing the seat pitch will result in higher price, thus making air travel unaffordable for many, whether a minimum seat pitch is legislated or not. Below a certain profit margin, a business becomes unworthwhile to operate, so there's a limit to how low the fares can go even if there is a level playing field for competition.