Whether the email is considered private or not is completely orthogonal to whether you are allowed / should tie an action to your email. And then again completely orthogonal whether you can/should make that connection public.
Even if your email is public information and even if what is uploaded is public information that doesn't imply that the email address behind the account that uploaded that information should be public.
The same exact thing goes for physical addresses too. The fact that I live at my address is public knowledge. But the presence of my address in any particular database, mailing list, etc. is not and should not be public knowledge.
i agree. if "user contacting another user" is a feature, there should be the option to (optionally) supply a different email address than your account email or use an online form that keeps your account email hidden.
Even if your email is public information and even if what is uploaded is public information that doesn't imply that the email address behind the account that uploaded that information should be public.