Having the Crew Challenge rewards only be accessible by completing the challenges would be fine, if there was a way to reset progress. Either an option in the challenges menu somewhere, or for it to reset automatically when you complete all of that type of challenge. Even if this was only available in TVHM, it’d be a massive step up from “once per save file”, as you say.
Without that option, I totally agree they should be included in the loot pool, in some way, so there’s more chance to farm them.
Ooh, I like this idea. Having some unique and legendary items locked from the loot pool, until you reach certain points in the story/challenges, where you get one as a reward. Not sure how popular it would be to have to unlock them each time, but it’s better than only getting them from finishing those missions/challenges.