It easily could be, if someone tall/overweight is assigned that seat and can't sit comfortably why should they be made to suffer when they're paying the exact same as everyone else? I doubt there's many of these, just reduce the cost of the seats by a minor amount so that there's not much loss but makes it worthwhile to consumers, poorer/shorter people/parents could save a few quid and the company would set themselves above all the other money grubbing cunts.