Keep in mind that this is just my opinion, and I know others have a different view of this, but I think that taking these courses is a tremendous waste of time UNLESS:
(1) They're required for your major
(2) You are truly interested in them
Med schools recommend these courses because components of them are covered, to some extent, in med school. However, as most med students would tell you, you do not gain much of an advantage by taking these courses. Much of the material is glossed over during the first few weeks of med school, and is often presented from a much different perspective (a clinical/pathological point of view as opposed to a broad/conceptual view) As far as preparation for the MCAT, yes, these courses help, but keep in mind that they are likely to go way beyond the curriculum of it. To me, you're better off spending your time studying the basic science and doing practice problems, then studying in depth details in these courses.
From an admissions standpoint, success in these classes (much like success in any science class) will help you, but since they are only recommended they won't hold it against you if you don't take them. I think these recommendations are made for your "benefit" (a benefit that I dispute) and are inconsequential from an admissions standpoint.
