I never actually thought of it that way, I thought Hase served his purpose for episode 15 when Kota has a reason to hate Yggdrasill, that seemed to be its ultimate conclusion.
The thing is, my thought on Hase is this: He's just a dude.
Kota doesn't need to dwell on him any more than just as "An innocent life that was lost" because his relationship with Hase basically amounts to "That dopey guy who fought me once", he doesn't see him as a bad guy for it either because, y'know, Kota's optimistic about people.
Jonouchi just seems to see Hase as a guy to push around, and his lamenting of Hase's departure just amounted to him wishing HE wasn't the one being pushed around by Pierre, at least that's how I read it.
And while I am overthinking how Team Raid Wild acts, they don't SEEM to rely on Hase as anything more than a leader, rather than as a friend they show concern for. When his Driver broke they were cheering him on in what looked like a "Don't let us lose!" sort of way. They just call him their leader and nothing more. And with his disappearance they seemed fairly nonplussed compared to Gaim's loss of Yuuya, they just carry on without him with new members showing up later (episode 18 - I read very deeply into these things XD)
But yeah, Hase is a dude. He's got story potential, but I feel they've already used what they could. He just isn't depicted as being close to any particular character on screen so there isn't too much to work with beyond Kota and how he cares about protecting people. At this point I can't see much coming out of telling Jonouchi, actually. :sweat: