You make a few interesting points here. Your idea is that, " The fact is, you ONLY need 1 year of Biology to do well. But those extra upper-div Bio classes won't hurt."
Those of you who agree with this statement, I'm not quite sure if you've gone through recent MCAT material or exams? Or even talked to people who have scored highly (12-13+). Most everyone I've seen hit those higher scores has said, "there were a few questions I could have only answered with my upper-division ___ course."
I would respond to that by looking at VR. Yes, anyone CAN answer the questions of VR... but it favors those who can read difficult material so taking those humanities classes will likely help.
You see, humanities majors in general will score higher on the VR section than science majors... but why? It is evident that anyone CAN answer VR questions correctly, why in the world would they consistently score better? Well, because they are so familiar with the material and they use the VR skill set often. In timed conditions, it helps to be familiar with material.
In the same way, a BS section with lots of advanced genetics or cell bio will be better handled by a bio major. As you likely know, they drop hints in the passages that help answer questions (must incorporate the info). A person well versed in the topic will effortlessly pick up the pertinent info. A person with basic bio will have a much tougher time and will have to do it under the pressure of time, which could mean missing a few questions because of the lack of familiarity.
So yeah, of course anyone with Bio1/2 can answer the questions. But anyone can answer VR questions too and some people can't score above an 8 on VR. I would change that "doesn't hurt" to "very likely to help".
I guess. You could also argue that a bioengineering major will have improved skills in Bio/Ochem/Chem/Physics, so he has improved in 2/3 of the areas vs only 1/3. Plus Ochem and Chem do a bit of overlap for anyone who knows their chemistry (chem majors). The guy who scored a 40+ on the MCAT twice was a bioengineer I believe (41 and a 42?).