Do you think all superhero and superheroine should wear a mask to protect his or her identity?

I do.

They have to in order to not have to pay for collateral damages incurred in battle or put loved ones in harms way.

Yeah they need to....Don't you see all the damage they cause, if they didn't wear a mask they would get sued.

Yes because without the mask everyone knows who they are, and to protect themselves, loved ones friends, etc add in everyone else finding them including the Authorties. There are exceptions such as the all mighty Superman,Superboy (Kon EL), Ghostrider because he is in his non mutant form, Collossus, and others I may have missed.

It is more about protecting their families. It's too late in the Marvel Universe for most of the guys, after the Superhero Registration Act era.

No - depends on the character. Some need to, some want to, some don't.