If you already have a good sense of calculus, there are definitely times where the calculus representations of the formulas can provide for a more direct conceptual intuition than the algebraic formula. If your calculus is fluent, it's just more accessible mentally to look at a representation of the work as the line integral instead of having to look at all that F cosine theta mess, or in electricity and magnetism, for example, it's really good to be able to read Maxwell's equations. Verbalizing Maxwell's equations a couple of times to yourself is good for MCAT prep. It makes the unity of electric and magnetic force and electromagnetic radiation present in a way that you just won't see without them, so calculus can definitely be helpful for the MCAT, though not for problem solving with numbers, just for understanding. But you already need to be completely comfortable with calculus for it to be worthwhile at all.
However, from a teaching perspective, there is a big problem. For every premed who has that kind of comfort level with calculus, there are ten for whom the mere sight is going to be counter-productive. For folks on the way to making a 13 or 14 in PS, the idea that there is another 'privileged' group knowing more calculus could be enough of a confidence destroyer that they come to believe that a superior score just isn't in the cards for them. I know from experience that a person can do great on the MCAT without any deep experience with calculus, so while it can be advantageous, there is no good argument for making an MCAT prep book with much calculus.
But here's a suggestion. For a person who doesn't mind calculus, I'd recommend getting yourself a back edition of Serway's Physics for Scientists and Engineers from Amazon for a few dollars. Just skimming through that book, looking at the formulas, and reading Serway's really really excellent discussions in weak areas can be a great thing in MCAT prep. I've made this recommendation before, so I know it can be helpful.
