If our hands are intended to have complementary roles, then consistent specialization to one side makes sense, because there isn't a useful continuum - a strong

If our hands are intended to have complementary roles, then consistent specialization to one side makes sense, because there isn't a useful continuum - a strong developmental preference would be more reliable. But since the middle of the continuum, i.e. no-preference, would presumably be the worst situation, it would be developmentally unstable and any tilt to either side would quickly become dominant. One possible "motive" for a particular left-right lopsided bimodal skill pattern.