And I tend to think of whether the savings really are worth it. Cart based games, it's not a big deal and youd can make good use of the 3DS holes for the design (too bad NoA doesn't give a shit, tries it once with Kid Icarus then abandons it again), but with discs? ESPECIALLY in this way? It's like the packaging equivalent of chainmail bikinis, except penny pinching instead of fan service.
Tend to think if you want to save on plastic you're far better off just making the cases as thin as you can while still being strong, and focus more on getting rid of stuff like unnecessary packaging materials for consoles, and on a society level ditching stuff like plastic bags. Basically focus on the stuff that's MEANT to be thrown out first.