I completely agree with your point, BPF, but I was basing my advice on the fact that quite a few students are not all that familiar with using CAS instead of IAS. For a 172R the stall speed at max gross is 47KCAS for flaps 30 but this is equivalent to 33KIAS. If a student takes up the advice to use 1.3xVs and he would base this on indicated speeds, he would then creep over the hedge at 44KIAS, admittedly that equates to a CAS that is a shade higher (approx. 50KCAS), but still too low for my comfort.
I have trained a lot of students on 172s using 65KIAS on final and haven't had all that many issues with that. I agree that a lower speed is certainly an option and have regularly flown approaches down to 50-55KIAS myself, but it is not something I would start with for a student.