I see some people on the OUSA forums are complaining about the changes to S104
But it's always been the case that you could skip books in S104 and still pass.
I skimmed the biology book and some of the geology and still got a distinction in the exam (just) by focusing on the physics/chem. I know other people did something similar.
So I think making that an approved option is a good thing. Certainly for me it would have been.