Consider everyone who lives in an apartment who doesn't have the option of replacing their lock (and I wouldn't really want to anyway... I rather prefer the unchanged external appearance of this product).

IIRC, you can also easily deauthorize users, so it's also the cheapest way I can think of to retrofit something into being a shared space where you want to be able to control access going forward.

It's not the perfect lock solution for every use case, but it's a really cool utility for a lot of purposes.