The new finding that exposure to sunshine helps limit a number of cancers is obviously good news to a Miami resident like myself.
On the other hand, too much exposure is still considered to be deleterious.
The advantage of being in the sun is that it helps the body build up its supply of Vitamin D. This helps various internal organs. However, the skin is damaged by having too much sun, as it has the tough job of being the filter, meeting the sunlight first and being abraded by the encounter.
To be honest with you, I have always assumed that this was the case, relying on the Biblical verse that it is a "sun of charity, with healing in its wings" (Malachi 3:20). Even though the main focus of that prophecy is on the end of days, the Talmud (Nedarim 8b) teaches that part of that healing power is already in place.