There are parts of e-cash that I like. Like you, I think it's cool tech. Privacy is a neat feature as well.

Beyond that, I don't really think it solves any problems. Because, again, as you pointed out, it's a rug factory. You have to rely on another custodian. And if most people are using lightning custodially, then they're relying on another layer of custodians to not rug them. 

I'm not sure exactly how it would happen, but it would be neat to see cashu as a pure layer 2 and not as a layer 3 sitting on top of lightning.