I'm suspicious of the claim that MCAT VR requires more critical thinking skills than the sciences. If this were true, people who score 12+ on VR wouldn't score <10 on the sciences, but it happens. The anticipated counter-claim that they didn't study the science material well is unlikely.
The problem I had with MCAT VR wasn't critical thinking but the allotted time. When I took an additional 10 or so minutes on a VR test, I would understand more and get more questions correct. Once most test-takers understand the VR passage, the answers aren't that hard to find. That's why passages are usually dense to create an added level of difficulty. I think this is the biggest barrier. Half of test-takers would score 10-11 given some extra time.
I don't have this issue with science since I read science material faster than random passages on Tolstoy and art weaving, and can even do it with less concentration.