Oh yes, please make the docker binary also contain an http server (oops, it has one) serving http webpages with websockets and shit. Why stop at containing container libraries, a certificate authority, a raft / consensus / key-value store thingy, leader election, parallel file downloading, signing and verification, a copy of nsenter, a tcp and udp proxy, and a scheduler.
I'm pretty sure including 20 different things that barely work is the only way to make a low-level bit of software better than including 19 things that barely work.
Really though, this should not be built in to swarm. This should be an "addon" which can be deployed on top of swarm (as the Kubernetes dashboard is a totally normal pod you run on top of kubernetes).
I'm pretty sure swarm's security model right now doesn't allow exposing services behind tls client auth or such, so there's no reason to serve this and leak information to the general public.
I'm not even sure why they had decided to make swarm mode builtin, rather than a layer it used to be.
Layer made sense. Pre-bundling it (using either OS packages or using Docker's own image/packaging system) would've totally made sense. A nice CLI shortcuts to get the layer up and working in a single keystroke or two would've made sense as well. Making that multi-megabyte monolith larger is not so much.