Ben, I think Adam means that he wants to restrict full users of the system from scheduling via the "Add Event" path rather than through a public form.

I too wish that I could just create different user groups so that each group only had certain spaces, resources and services that they were allowed to reserve.
I also wish that all public forms weren't treated the same in this regard. For example, I would like to have one public form that allows only conference rooms to be booked but another form that only allows certain classrooms to be booked. I would then only publish the link for the specific form to those specific people.

Wouldn’t you just not allow the space to be bookable by public?