In the Family Editor, you can Associate "Visible" to a parameter.
But more often than not, when you have one thing Visible, you have something else that needs to be hidden.
Currently, you must create another parameter and make it's formula = not(OtherParameter)
If we could simply use not (OtherParameter) directly in the Associate box, it would save a lot of duplicate, single-use parameters and clean up the long list of Family parameters.
Perhaps a checkbox on the Associate Family Parameter dialog to toggle Visible or Hidden