It's a great question. With custodial Sensei and use-cases like you describe lnbits/lndhub are probably better solutions.

We are working on integrating with the VLS (validated lightning signer) project to enable remote signing for all of the nodes run on a sensei instance. Once this lands you'll be able to spin up your own personal blockstream greenlight alternative running entirely from your own instance instead of relying on blockstream's servers.

There are likely some other use cases, maybe in gaming, where you (as the game developer) don't want to deal with the regulations that come into play when you are custody'ing bitcoin and so sensei w/ remote signing might be a good solution.

Even without the remote signing, there might be some research-y use-cases around simulation/testing different network topologies where you want to simulate and control thousands of nodes easily.