100% if you're moving into Liquid or LN from on-chain you meet the same on-chain cost so do you go custodial LN (trust 1 custodian/LSP), run your own LN channels (technical overhead, and stay online) or go Liquid which gives you a similar UX as on-chain for those who aren't ready to make the leap to dealing with a new ecosystem with invoices, address formats etc.

I think the use case is to buy L-BTC directly with fiat or stablecoins to build a stack or make payments and you could move to LN with that via a swap service and vice versa

Could even use Liquid as a secondary storage option for sats to rebalance a channel

Who knows? Liquid blocks are still pretty much a ghost town but relatively it has picked so people are clearly discovering it and using it for some reason they didn;t have before