But Ellen, not everyone likes the centrefin. If you want to sail in shallow water, it's a drag (literally). If you want to sail upwind at high angles and then plane fast downwind, it's a problem. Lots of times on longboards you want full centreboard upwind and no centreboard downwind, and you can't do that with a centre fin.
The move away from a fixed centreboard (like in the original Windsurfer) was the second development (after small sails) that windsurfing did, I think. Taking us back to something that gives us even fewer options than the very first board ever made seems a bit odd.