Maybe it's a case of diminishing returns -- with every change the effectiveness of the biomod decays, until it breaks in some unpleasant, probably fatal, way. (It's got to be unpleasant, or people will adapt it into a cure for catgirling or something.)
-- Bob
---------
Then the horns kicked in...
...and my shoes began to squeak.
-- Bob
---------
Then the horns kicked in...
...and my shoes began to squeak.