Just upgraded at the gate LHR-YYZ, to PY. Noticed I'd been given a middle seat even though there were 10 empty seats in PY, including 4 aisle seats. I found the concierge at the gate and asked them to change to 14D, an aisle seat in an empty row. But many people wouldn't have even known they were in a middle seat until they boarded, know how to see whether there were better seats even if they had noticed, or know how to get that changed.

Is this the system working as designed?