I think it's a bit of a semantic argument. We clearly have different definitions of "one-dimensional". Mine is far more simple. If a RB isn't a threat to catch a pass, then I view him as one-dimensional. Doesn't matter to me if he's more dynamic as a runner than an Antowain Smith type back. When Damien Harris is in, teams know they don't have to really cover him out of the backfield. That doesn't mean that he doesn't have value in a variety of running formations, which he clearly does.One-dimensional is a bit harsh. A one-dimensional back is someone with one skill that defines them in the role. Antowain Smith was a one-dimensional back. He was big, strong, and slow. His only thing that defined him as an NFL back was his play strength.
Harris is big, fast, can run downhill, can cut back, can jump-cut, and has a ton of versatility as a runner. He may not be a pass-catching back, but I don't think of him as one-dimensional in any way, as I think that does a disservice to his skillset that allows him to gain yards in a number of different ways and schemes.
If Rhamondre can become a bigger threat out of the backfield, then that's something the Pats haven't really had in a lead back since, I dunno, Dion Lewis?