The difference between patina and cruft
Cruft is obsolete. Cruft is broken, discarded, non-functioning refuse that should be hauled away.
Patina is the wabi-sabi of positive use. A bookshelf of well-worn encyclopedias (now replaced by Wikipedia) has a patina to it. Simply seeing it reminds us of the possibility of discovery.
Patina makes it easier to go forward. Cruft gets in our way.