The plastic bags are useless heat sealed things, very much single use and can lead to serious Lego explosions and lost pieces if not opened carefully.
I think their research is long term and commercially driven as well, it’s not proving easy to replace the current materials, proper Lego is highly engineered to precise tolerances, material characteristics are vital for it to work properly, many times over.
Anyway who puts it back in the box, doesn’t everyone have a wall of Lego to keep their spare bits in?