Hmmmm....interesting topic this is turning out to be, as opinions seem to be divided
Yourself and a few others believe its needed and then I've spoken to some racers over here who believe it is not neccessary!!
I have no cracks where you mention (yet!!) but suppose there is no harm in fitting them.
If I find some, I'll probably fit them..........better get it running again first anyway!!
Cheers.