This is a nice high-level API for (more) reliably handling networking, taking a fair amount of load off developers having to implement it themselves. Of course it would be nice to have an API like that available as cross-platform library.
ZMQ is not a 'neutral carrier' and can't interoperate with things not implementing the protocol. It's great for the intended use case, but it's not a general purpose replacement for the Berkely Sockets API.
I agree - it's a great tool and useful for a lot of things. However, it's not useful as a general purpose network stack, which is what Network.framework is.