I am mainly a sealed collector so I try to answer your question from my point of view.
First of all I don't have enough space to display every single bit that comes with a ce. The boxes tend to get bigger and I'm already struggling to arrange the boxes alone. Can't even think of displaying any of its content.
Secondly, it's already hard enough to keep those boxes clean from dust. I don't want to clean all the bits and bobs that come with them. (Just saying this because I cleaned my room all morning long,
)
My third reason and probably the oddest one is that I like the feeling to know that all those lovely things inside the ce's never got touched by anyone after they were sealed. I like to think that they stay there forever and no sun and no dust can harm them inside their boxes.
Though, I do open up first Editions that come with the game and some dlc only to play them
