I think it's really a blending issue. With the thicker flavorings, like Caramel, Dairy, Double Chocolate, they create a longer blending (steeping) time and will tend to mask some of the flavors and sweetener that won't start creeping out until they've sat for a couple of weeks.
Flavorings are just that, flavorings. And will not likely taste the way they're supposed to taste until the OTHER component, sweetener, is added. So if you got an unsweetened German Chocolate Cake liquid. The components will taste like a GCC tastes, but something definitely missing without that sweetener to set it all off.
If it's a simple matter of an aversion to artificial sweetener, or that it may be creating a necessity to clean your attys/cartos out more frequently, sure, this is understandable, but as a necessary flavoring component to make the flavors pop and taste the way they're supposed to, we recommend the sweetener.
But we like to leave the decision to YOU, rather than just standardize the process and add sweetener to everything by default, and so you have the option to have it sweetened or unsweetened.
