Great question. I like that when the city lifeguards show up in the summer I can still windfoil my guts out from the old windsurfing and small boat launch error whereas kiters are relegated to a beach with a dangerous wind shadow and rocky launch that's effectivly unusable at all but the lowest tides. Our beaches are super overcrowded in the summer, hence the kiting ban. I like that as a windsurfer it's way easier to become a windfoiler than it is for a kiteboarder to become a kitefoiler. The hardest part about kitefoiling for me was board management when body dragging, with windfoiling I just climb on uphaul and go, no awkward bodydragging with an ironing board. Most importanly, though it's the wind where I live, it is often short-lived and terrible. While the guys on the ram air kites can get going a couple knots earlier than me on the windfoil, when the wind tanks I can still float home, I got sick of the self-rescues with my single strut kite on the light wind days. One other bonus I recently discovered is that my windfoil board doubles as a wingfoil board, so I've been having fun with that too. If had better conditions locally ie, less crowded beaches, less annoying lifeguarding policies and better winds, I'd be happy to just kitefoil and I have a lot of respect for the guys here that put up with all the @$%^ at our spots to get out on the water and make it look easy.
oh one more thing, downwinding on a windfoil doesn't require me to worry about line tension, I can just flag the sail and ride the swell. Unfortunately it's so rarely good enough here for me to do this most of my foiling is flatwater.