Critical thinking is actually more useful than people think.
Imperial did not look at my Critical thinking grade for admission. However, i decided to take it through to A2 simply because it was the one subject that i could achieve high grades in without actually doing anything that resembled work. Imperial have made me an offer, including CT as one of the subjects that i can get an A in.
So in short, Critical thinking = easy A = one less worry for getting in to study medicine.