I believe that as these drinks tend to be more expensive than the basic products because of the extra time and effort required to produce them, and as they appeal to a more discerning demographic and are not implicated in the binge-drinking culture, applying the same level of duty to these as to the basic products is nothing short of punitive.
Current duty levels are hitting both the breweries/distilleries and pubs very hard so although it may appear counter-intuitive, reducing the duty on these premium products would not lead to a reduction in duty and taxes recovered as people would be more inclined to buy these premium products. This would have the added benefit of protecting employment at the breweries and distilleries, thus ensuring a continued income to the government in the form of income tax and NI from the employees and in the long run, more revenue to the government, not less.