You're right, for most simple use cases it doesn't matter. But I once spent an hour on a weird bug that turned out to just be some plugin applying a map that I didn't know about and that I didn't know about map expansion. So I might be biased, but I think a loose understanding is helpful.

The default behavior is to recursively expand and apply your mappings and "noremap" disables this recursion. For example if you do something like

  :map j k
  :map q j
  :noremap w j

q is expanded to k, but w is expanded to j