Why doesn't WWE utilize more retired legends, in limited capacity, as managers/mouthpieces/on-screen mentors?

I could see some interesting pairings like Dean Ambrose and Terry Funk.

Or play up the Samoan heritage in a meaningful way by having Roman constantly seeking the approval of his elders.

I don't think pairing guys with older superstars for a cheap pop is the right idea. I was thinking more along the lines of Zeb Coulters role. Dutch is not a guy who is immediately recognizable to a large portion of the audience, nor was he ever super over with the WWE crowd. But he is a journeyman who knows the business and adds layers of complexity (at times) to story lines.