If you knew there was a risk of a microburst and you started picking up a massive tailwind, it may make you think twice about continuing the T/O?
Great theory, but useless in practice. Apart from the distraction of looking at a tiny wind vector arrow while barreling down the runway, trying to keep straight and monitor engine parameters with a "massive" tailwind, how could one determine whether one has already used up the stop distance? Any V1 based on indicated airspeed would be useless if the tailwind was so massive.
As for the aircraft displaying wind direction with any degree of accuracy while on the ground - it's poppycock!