If you're bootstrapping random servers, this is a fine approach.
The whole Salt connection methodology is 'trust on first connect' (a bit like the default SSH) with a manual stage in accepting an incoming request and the connection stream is encrypted.
If you're using salt to bootstrap your VPN servers or network appliances then it's understandable that you'd have it exposed to a more public network, and the documentation was clear that this was fine.
Not everything is a virtual machine on a cloud provider.