Lot's of comments here at the "micro" level: about the comfort of an individual pedestrian. There's also the "macro" view: how best to quickly and safely move a large number of pedestrians in a short window of time. The PATH mostly connects Toronto's financial district full of office towers and 9-5 workers with a transportation hub, Union Station, at its south end. Union Station gets around 300,000[0] passengers a day, most but not all are office commuters. Without the PATH, the sidewalks would be absolutely (and dangerously) jammed between 8-9am and 4:30-6pm.

[0]https://www.toronto.ca/services-payments/venues-facilities-b...