Explicitly Mark Optional Customer Details

Maybe I am missing something, but right now customers do not know which fields are required and which are not before they hit submit. Example:

Could we add an explicit information about that? Something like that (could be configurable as a boolean flag):

I would like to collect website, photo, and additional things from people who want to share that, but I am OK with only name. However, I am afraid that without explicitly stating that, some clients may leave this page.

Note: I know I can do that through custom label