Absolutely it should have non-combat roles. See this is an update that could have been a real game changer for things like exploration, mining, and trading. Real depth could have been added to those parts of the game with multi-crew.
Navigators with advanced tools in system and galaxy map to find interesting bodies while exploring, or can help finding best trade routes.
Engineers that could tune a ship on the fly to increase jump range, or boost shields during combat, at the expense of other modules. And of course the ability to repair modules.
Scientists that could take core samples, collect more precise data, access to different scans.
I feel like these roles could have added so much more depth to roles that have so far been a little boring if I'm honest. They could have even made it accessible to single players if NPC crew were available to fly your ship while you take on an alternative role. But alas, we're left with only 1 new role, gunner, and a second SLF, roles that are completely useless outside of combat. Sure, it would have been a lot more work, but I would have been willing to wait on that.
HOWEVER, I do understand FD's decision, and I'm not really upset with them. I'm convinced that there will be further development on multi-crew down the road, I think a lot of things will grow over time, but right now it seems we're in the placing module phase, I believe, and hope, that the fleshing out phase is coming. They seem to have a long plan, and I trust them.