I use it for 2 reasons:

1) there's an exchange I use that doesn't support lightning... So I can send 100,000 sats on-chain to a peg in address of liquid. This gives me custody of smaller amounts of BTC until 1M sats. Can't use alby hub in this instance.

2) I like to try and get waiters/waitresses to accept their tip in BTC and it's cheaper to send liquid address to liquid address, and not give a newbie the headache of managing a channel and they still take self custody.