The introvert/extrovert dimension is as predictive as the identical dimension in the Big 5. I've made great use of knowing when a colleague, friend, etc. is introvert or extrovert regardless of which test told used. Even if MBTI didn't quite hit the mark historically, I don't see why there are so many haters. It's part of working towards better models. It's a worthwhile pursuit to try to characterize stuff like personality. MBTI is strictly more useful than Astrology just as BIg5 is strictly more useful than MBTI. Future models will surpass these with things like hybrid self-report + neuro-imaging approaches. People really seem to feel threatened by being characterized though. It's a bummer.