I mean, he pinned Rey to get a title shot, so it's far from the worst possible use for him. He might as well be the top 10 greatest professional wrestlers ever, but he is not beating time: he is 48, turning 49 this year, so he should be used to be featured alongside newer talent.
Like, I get not liking his nothing program with Karrion Kross, which basically went nowhere, but being pinned in a multi-man title shot match is not bad!
And, like, Gunther's reign IS a pretty damn big deal. It's already the longest in this century AND one of the longest all-time.