It's ugly but very practical. But they should decouple the frontend from the backend, and give users direct access to their private keys like nsecs or as 12 word seed phrases. Otherwise the different instances aren't interoperable with each other. Also, without decoupling the client and server, you are forced to keep using their web implementation, which is not ideal for most privacy conscious people. Another thing is, they aren't very pro-bitcoin, so the paid instances only accept traditional fiat payments which is terrible for privacy.

Another thing is it's a product, not a protocol. So creating another compatible implementation is not going to be very easy, and forking the mostly JavaScript code is not going to be easy either