The boxes have no yellowing because almost nobody would display them. What is remarkable is that they haven't been bashed or crumpled. When a pound sterling had value against the US dollar, I would have been very tempted...

What to do with them? Create a nice photo montage, frame it and display it next to your perfect Mac 128K.

MacPlusOwner asks about shrink wrapping. Re-wrapping a software box is trivial because the contents can be removed, copied and replaced without messing up the packaging. However, anyone who has attempted to repackage hardware for return to the supplier will appreciate that the process is close to impossible, even when you are NOT trying to hide that the box has been opened.