My guess is that the AAMC wants this new scoring system to mimic the scoring of the USMLE Step 1 exam. That exam has a 3-digit score, and now the new MCAT will as well. They say that doing well on the MCAT predicts how well you'll do on the USMLE Step 1. I don't believe that for a hot second. For one thing, most of the stuff the MCAT tests you on will not be required for you to know in med school. Also, the USMLE is vastly different in structure and content.
I personally despise the MCAT, especially the new overhauled version. I'm only going to take it to "go through the motions." The new test is longer and more grueling, incorporating 3 more subjects into the test. The AAMC reports that there will be 130,000 or so physician shortages by 2025. With this new MCAT, it's enough to make people turn away from the field of medicine! Why would an entrance exam get harder when the USA will be faced with physician shortages in the near future? Doesn't make any rational sense to me. Merely increasing med school enrollments isn't enough. You need to attack this problem at the source, and that is the admissions process.
When I take the MCAT in 2016 and apply to med schools, I'll be focusing on my state schools, a couple of ivy's, the Caribbean, England, and Australia (basically any foreign country that has ties to the U.S. gov't so that I can secure federal student loans). I think this is an excellent strategy to take. Scores and results from the new MCAT exam will still be new in 2016, so I don't think med schools will have a good grasp as to how the mechanics of the new test will be working out. It will take a few more years of data analysis to come up with any sort of idea as to how the new exam is working. Therefore, I think most med schools (especially foreign ones not familiar with the new MCAT exam) might be more lenient on the applicants because the MCAT is still in an "adjustment period."
Maybe I'm crazy to think this way? I don't know, but it's just a gut feeling I have. The time to apply to med school is now...2015 to 2018 look like prime years to apply from an MCAT point of view.