It’s not useful for myself. But it’s useful when I am testing and I am rugging myself. However, since it is a bearer instrument, if I send it to someone else, it suddenly becomes a liability.
Discussion
So you're thinking of it as a simpler and custodial forms of payment channels perhaps? E.g. I wouldn't immediately cash your zaps, but keep them for a while, and efficiency increases if I then cash them in all at once later?
Exactly. If those ecash tokens are encumbered to me, I can wait until I accumulate an amount before I clear out.
Few years ago on a podcast I shared how I use lightning to "borrow" against my UTXO's to acquire more Bitcoin, all self-custodial with no counter party risk*
Been working for years.
*nothing is perfect in this regard (except for cold storage priv keys) but this is the closest thing we have imo