Edit: just noticed an actual Nomad user replied as well, and I like their answer better. Consider mine an addendum. :)

Batch workloads rarely require Consul, but for deploying your standard network services on Nomad: Consul is basically required. You could likely use any number of service mesh systems instead (either as sidecars, Docker network plugins, or soon CNI), but you'll be doing a lot of research and development on your own I'm afraid.

The Nomad team is by no means opposed to becoming more flexible in the future (and indeed better CNI support is landing soon as a first step), but we wanted to focus on getting one platform right and a pleasure to use before trying to genericize and modularize it.