My impression has been that they were experimenting sonically, looking for new sounds. Sometimes the result seems flat and dull to our ears 37 years later, and sometimes absolute brilliance emerged (viz: The Ballad of Dorothy Parker). But the result was always something quite distinct from the sonic landscape of its time, and it had a huge impact on music production that followed. For example, it's hard to overstate the influence of the mid-80s Prince albums on the entire genre of New Jack Swing.