Stumbled onto this episode of Developed last night.
They discuss why using sweetener is absolutely necessary, but more interestingly which sweetener to use with which profiles (and why).
I use very little sweetener and most of the best mixologist's i know rarely use it so it isn't necessary at all but if it's on Youtube it must be true! i find most commercial juices use a lot of sweetener to hide the poor mixology especially with juices from the States! The only thing i do agree with when adding sweetener does enhance the recipe using the correct one for the profile is important!