If they do not need it why would they sit in the sun in the wild?
To assume they do not is not wise at all, nocturnal animals do not require it but all day animals would.
We humans benefit from sunlight, we suffer without it.
It helps animals digest food, it helps with Calcium D3 digestion...and with other vitamins.
A night time bulb such as a moon bulb is suitable if you want to view your animal.
Or a red infrared bulb will provide heat and will not stress out the animal...these are used for reptiles and all manner of animals.

I think that many who do not use UV lighting do it to save money, there is proof that UV benefit animals.
As Soldierwillis and Lija said the animals colours brighten and so it means that it must help their health.
I know when I had my sav monitor I noticed the same.

I think the advice people are giving concerning UV lighting and animals should be rewritten, specially with animals which sit in the sunlight.