When I've travelled by air, "comfort" has never been the first thing to come to mind as I've shuffled through security, sans belt and shoes, hours before my flight's scheduled departure time.

I agree that there's a lot that's impractical about hovercraft - especially when for crossing the channel there's so much competition: ferries, the tunnel, and (as you mention) flying. For people who want to take their car across, as I understand it the hovercraft took about as long as the eurotunnel does now to cross the channel - but the tunnel has much more capacity.

I’ve been on the cross channel hovercraft in bad weather. It was just as bumpy as being in a small speedboat in bad weather. But it was huge and insanely noisy and the experience seemed to last forever even though in all of that sensory overload I had no real concept of time.

If it had operated closer to Cuba the Americans would surely have used it as a form of torture.

Unless you've experienced a hovercraft in chop, it's probably hard to imagine. It's similar to extreme turbulence but more jarring and for the entire flight.

Hydrofoil from Sorrento to Capri in choppy seas, on our honeymoon. Was the stuff of nightmares. My wife said we’d have to live on Capri because she was never setting foot on a boat again

I went on them multiple times. When the sea was rough the crossing was incredibly rough. When it was smooth, crossing into France straight up a beach felt like magic.