No reason unless you want more gears.

I will say this Some hubs can have the freehub swapped to make it able to run the 8 and 9 speed. The Shimano stuff this is a VERY easy swap. The one set of campy wheels I have looks like it would be a easy swap as well but my wheels are a little newer then yours. My wheelset comes set up where you cane set it up for Campy cassettes or swap the freehub to run the Shimano cassettes.