I did 3 years of a math PhD, and am working on a computer science MS now. My admissions essays were both much shorter than they asked for, and were both along the lines of "$subject is a whole lot of fun. I have done some cool things with $subject. I would like to study $subject more, so that I can do more cool things with it. These faculty members in your department are doing some awful cool things with $subject, I sure would like to do some cool things with them." MBA programs might be different, since I don't think anyone has ever said "business is a whole lot of fun" with a straight face, but I think you're probably stressing about the essays more than you need to.
It's possible. I also realized I'm out of practice at tradional structured essay writing. I wrote two "career stories" before I realized I should be going for a persuasive essay, complete with thesis, topic sentences, and supporting paragraphs. (I think the structure will not only help me focus but help me feel better about what I'm writing.) I think you're probably stressing about the essays more than you need to.