This guy has been one of the longest running background characters in Thor and one of the least developed. But if you think about it one of the most important as well. When Thor is off on adventures and Odin is off on his secret missions, hunting, or fighting the Vizier often comes across as the guy who kept the kingdom running. He takes care of all the minor details that Thor finds too boring and Odin either doesn't have time for or finds boring as well. He was a combination of adviser/wizard/chief bureaucrat. He is the type person you might find annoying, but is in many ways essential.
Would anyone be interested in even a short story exploring his background? How he came to be the Grand Vizier. How long he has been at the position. All the secrets he knows. I wouldn't be surprised if he knows the ins and outs of Asgard's government and laws better than Thor or even Odin.
... from the Thor comics I read growing up, especially his appearances in the Defalco run (as I recall). That said, I can understand why modern Thor writers haven't really been drawn to him, the reason being, as you say, that he appears to be a sort of functionary, a character who handles the everyday business of Asgard, the way for example Maria Hill might handle the everyday business of Shield. But it's Asgard, so writers don't feel the need to deal with the nuts and bolts of how it operates.
He was, I think, a bit of a holdover from the Kirby days where Asgard was part mythology, part campy-techno wonderland, with a bit of King Arthur's court thrown in. In that world, he fit right in, but in JMS's Asgard he certainly had no place. And I doubt Gillen would use him. He's the kind of character that could potentially be used by Fraction, I suppose. Fraction seems to be into the wackier side of the Thor mythos. But anyway, he's strictly a supporting player imo. He's the kind of character that you might use if he were already there, but that you might not ever get around to re-introducing when he hasn't been around for awhile.