I wish I didn't need a UV filter for XCD lenses, but their design, with the front element so close to the terminus of the lens means I need to either always use the lens hood or keep a UV filter on.
Honestly, through decades of using Leica cameras and lenses, with the aforementioned issue of the M8, I've never felt the need to use a UV filter. But then, on a trip to the desert in Utah, I scratched the front element of the SL24-70 lens that was to be traded in on my Hasselblad X2Dii kit. Merde! When I got to the camera store where my new camera and lenses were waiting for me, the 24-70 was deemed too damaged. As soon as I saw the way the XCD lenses are built, I immediately purchased UV filters.
Back to the question of whether the Hasselblad UV are necessary. I don't know, but I bought them anyway in the belief that I was investing in a whole new system, and it was worth protecting the image quality with the highest quality filter. It may or may not have been needed, given how good other filter brands are, including Urth and B+W.