one that i use frequently is for demoing lightning use cases that are not obvious to people, like jukebox, split payments, dice game etc
other usecase is for simple payments api exposure for prototypes, also alby backend as i have lnbits running separately from my nodes that are locked down
I use it mostly to onboard merchants. Helping them, to start accepting BTC in their shop. LNbits can be used for many use cases, is one of that cover a broader panel of usage.
Testing it a lot, I end up writing a lot of guides and also the documentation wiki for LNbits.
And many more... the 30+ LNbits extensions offer a large number of use cases.
LNbits is exactly like a Wordpress for your node. You can use it for many things.