Bunkai , the essence of karate

A lot has been said about bunkai and what the true applications of the katas are depending on the source I believe through my own experience and research that it is a viable way to understand the Katas but, is it necessary ? With the advent of full contact styles and mma, bjj does the study of bunkai still gave a place in martial arts training or is it enough that karatejas do full contact sparring and do resistance training with kihon ?