Judy and I have actually discussed this. For the hobbiest keeper, we believe that if we recommend warmer temps that have worked for most of us, and the keeper is not able to keep their temps quite that warm - at least in their attempt, they will be keeping their animals in a healthy range. If we recommend cooler, then the average pet keeper might feel that they can drop even cooler than that, which could be detrimental.
In the past year, I have found myself realizing from reading the Barker's book, NERD's book, and other keepers, that there really are many ways to successfully keep these animals. I don't freak out so much if my temps dip a bit in the evening (because I do keep them in the warmer recommendations) and to quote BT - "do what works for you!"
Great answer! I agree, that for the average person it would be better for them to shoot for the higher temps than settle for the lower.
"If I were stranded on a desert island and could only have one book, record and person...I'd probably die of exposure."