I don't think we
need caffeine, but I for one am not giving up my 2 or 3 cups of coffee in the morning!
I think it's fine in moderation. If you're only having one diet pop a day, I wouldn't worry about it. The problem I have with diet pop is that it tricks your mind into thinking you're getting sugar, and that can cause cravings.
I have a bit of an addiction to it myself.
Sometimes we just need that little "kick" mid-afternoon...
It's not easy staying energized when all we want to do is cozy up for a nap.