it won't hurt to have it - it just isn't necessary. With many diurnal lizards it is absolutely essential as the lizards need the UV to make the pre-cursor for vitamin D3, which in turn allows the lizard to absorb calcium.
Some breeders dealing with diurnal snakes actually do chose to use UV lights to better simulate the natural environment and so it helps stimulate breeding. (The snakes would naturally receive the UV from the sun's rays.)
This isn't required for corns, but it certainly won't hurt. I used to use UV for all my corns, although I no longer do.
Skye