A secure RNG. Constant-time cryptographic primitives. A secure keystore. These are the sort of fundamentals from which a wide variety of richer applications can emerge. Just look at some of the use cases  that finally become possible.
Please note: The API is rough. Very Rough. There's still a huge gap of known issues and missing normative text, and undoubtedly more than a few typos. That said, hopefully this document captures the idea and vision for what we're working on, and with feedback, can actually achieve.