I have to agree with terry12 here. There is a reason why Essay A (What matters most) *always* had a recommendation for the most pages. Stanford cares MOST about who you truly are, whether you know yourself well, and if you're the right type of person they want to have in their class (and change the world). Goals and leadership are great and all, but with such a small class, high yield, and high amount of applicants, they can fill their class many times over with top candidates. Your only distinction is in Essay A.
Of course, none of us are on the admissions committee nor do we know insights into how they select people, so you are free to allocate only 250 words to the essay if you firmly believes that it's in your best interest. Good luck!