The issue with the old setup is that the bottom pintle can break where it is welded to the fitting. I had it happen to me on my old J24. Drilling a hole for a cotter pin would keep the rudder from lifting up out of the gudgeons, but does nothing to prevent the pintle from snapping off.
The new setup should have a gudgeon above and below the pintle fitting on the rudder with the pin going through all three. The cotter pin is just there to retain the pin. There is a lot more strength there and if the pin ever starts to wear out, it’s replaceable.