I actually agree with you that 4x2 isn’t a major buff, when I speak about major buff I am usually speaking about a 4x10 inventory, coupled with a 4x10 charm inventory, which is what people usually are talking about when adding a charm inventory.
I agree 2x4 is not a major buff. It’s another reason I think the idea of a small inventory isn’t worth the change. If it’s only enough to pick up an item or two, just run without those extra couple charms, and without the cube, it’s plenty of space. I run without full charms on many chars, the only time I might run full or cube-shuffle is if I’m having fun feeling overpowered and want to 100%it.