My argument is not that the supercharging situation makes a trailer hitch useless. I think that Tesla's concern is it exactly the opposite. If they included a trailer hitch on the Y, all of a sudden there would be a ton of Tesla's towing trailers.
And if a bunch of people started showing up at superchargers (with the current charger design) with trailers it will be a huge mess.
How many people realistically tow trailers? Trailers seem pretty rare from what I've seen. I feel like most Y/3 owners just want a hitch for a bike rack.