Some interesting thoughts here about seating and also mobility. Was surprised to hear about the rule in the EU. Would certainly make it harder to ask to use the toilet if you need to ask everyone to move and wait while you transfer to an aisle chair (and again when you go back)! 

https://wheelchairtravel.org/passengers-reduced-mobility-same-row-aisle-seat-safety/

wheelchairtravel.org

Thoughts from the Aisle Seat, in a Row of Passengers with Reduced Mobility - Wheelchair Travel

Three passengers with reduced mobility in the same row? The rare situation raises important questions about airline passenger safety.