Why not always use the :tag of a widget in Custom?

[Lennart Borgman (gmail)]

If a widget type has a :tag property this will be displayed sometimes in 
Custom, but not always. It will be displayed when you have a complex 
type like

  :type '(choice (key-sequence)
                 (color))

but not when you have a simple type like

  :type 'key-sequence

Wouldn't it be useful to always display the :tag property?