This pretty much describes it for me. If i had the choice between two tickets, one with a few inches extra space d one $100 less, I would opt for the extra space, and in fact whenever premium economy was in that ballpark I did so. But, most airlines ask big upgrade fees for extra legroom, and there's no way to know the legroom situation until you're boarding. The market is incapable of resolving this since airlines don't give you the information you need to make an informed choice.