My use case is that there are a bunch of custom fields and if someone had to answer–or even scroll through them all–on the new user screen it’s a UX disaster.
It would be really great if there were a “don’t show on sign up modal” option for custom variables (and apparently things like the web site field).
EDIT: Hmm. Well, your signup page doesn’t have web site and location on it, but it is on the profile page.