Because our intuitive concepts are so muddled and not as clear-cut and useful as a stipulated definition such as the IAU's definition for 'planet', I fail to see why clarifying our intuitive concepts is a good use of all that brain power.

OTOH, there is a class of fallacies (the True Scotsman argument, tendentious redefinition, etc),which are based on getting stipulative definitions wrong. Getting them right means formalisation of intution or common usage or something like that.