EDIT

currently it is possible to choose both "supports categorical data" and "supports quantitative data" for a feature, which is even possible as one can always handle quantitative data also as categorical data by defining ranges of values as categories. However, using the "Change Type" button in the DescriptionElement Details view does not change between all these 3 types (including TextData") but only switches between TextData and Categorical Data. I wonder if we could remove the button and replace it by a dropdown field which allows choosing from all available categories.