There are many nude rock impulses I can understand: sexy singer, looks good naked (Bow Wow Wow, Boss Hog); fashion (Prince, Buckingham / Nicks); defiance (Slits); unemployed tube sock (Chili Peppers); transgression, shock, titillation, art, and whatever Herbie Mann was thinking. Then there's what these bands are doing. In some cases, it looks like a defiant over-identification with hippiedom, like "we are your children and we are unclothed!"; but what are Orleans, Pablo Cruise, Steam, Styx and Man trying to say? My best guess: "Bros Before Hos".
Update: all the links above now work - sorry about that former plethora of suddenly dead links!