I don't know about your Grandparents but when mine passed away they had so much junk saved for a rainy day. Literally 30 pairs of shoes. What is that for?
You pay for that square footage in rent, you pay for it by having to manage in your house, you pay for it in the uncertainty every time you look at it.
You're never going to read that collected works of Shakespeare. Well, maybe you are. But if you have to ask yourself the question, you won't.
Sure, it's fine to have some "art" around in the form of books, or nice plates. But being dishonest with yourself contributes to so much frustration. This is extra true if you're living with someone.
This is all hard and fast (people have different circumstances), but the whole "fitting your life into a suitcase thing" is valuable advice. So is throwing everything out that you haven't used in a year (one of Kondo's thing).
It might be worth experimenting with the ideas "organizing consultants" give. It's liberating to actually be able to use my entire desk.
Yes, my parents taught me how to clean up. But they also taught me to treasure books, but running a library takes time beyond just "having a shelf".