Yeah, Ertz is probably is a little better route runner, and has a little better hands than Maxx Williams, but neither does he possess the strength for YAC, or blocking ability of Williams.
Williams was a vicious blocker. Just moving guys right out of the picture frame. He would also occasionally shed a tackler, and would move the pile forward (or at least fall forward) after contact.
Don't get me wrong. Ertz is sure handed, is producing, and I'm thankful we have him. But call me crazy if you want, I think Williams brought a little more to table, and I hope he comes back at 100%.
Agree with your overall take that our WR corp is not nearly as good without DHop. Very average in fact.