Seat pitch is the legal requirement NOT legroom...
Not so.
The following is an extract from
this document issued by the British Air Transport Association.
The United Kingdom is the only country that has regulations defining the minimum size of passenger seats and the space between seats. These regulations apply to all aircraft registered in the UK. The regulations state that the minimum distance between the front of the back support cushion of a seat and the back of the seat or other fixed structure in front should be 26 inches (660mm). This distance is designed to ensure the rapid and safe evacuation of passengers in an emergency. This dimension is not the same as seat pitch. Consideration must also be given to the thickness of the back support and cushion which will vary with the type of seat but is on average about 2 inches (51mm) thick. In practice, the minimum seat pitch necessary to comply with the regulations is 28 inches (711mm).
So while there is no legal requirement for legroom, there is a legal requirement for the space between seats, and that minimum is 26 inches. Let's just agree to a draw.