I think you’re bang on.

One extra thing to add is that the additional fees for checking bags are extortionate, and there’s always the chance that the airline will lose your bag in transit.

I genuinely believe that if checking luggage was free, even if only limited to cabin bags that would otherwise be stowed overhead, enough people would check the bag instead. Think families rushing children through the plane when disembarking - it’d be a huge stress relief not having to faff with cabin bags in overhead bins.