Rounded corners are friendly. It's almost as if they say "come play with us, we won't bite or cut you". Sharp corners on the other hand are more like "I'll cut

Rounded corners are friendly. It's almost as if they say "come play with us, we won't bite or cut you". Sharp corners on the other hand are more like "I'll cut you if you come near me." Perhaps this means that one can constrain user by placing sharp corners on contextually unavailable objects, and rounded corners on available objects. Speaking in terms of progressive disclosure, one can animate sharpness of the corners depending on if the users need to interact with the info inside of the corners. Then it's more like "oh, ok, now I won't cut you -- you're cool, boxes around me told me that, come enter me".