I do nont think the Steelers "need" a dynamic TE. It would be a luxury to have one, however, I hardly think they "need" one. There are other things on this team that they "need" more than a dynamic TE. And behinds I think the one they have is pretty solid.
Add a physical big wide receiver who can beat a press and add a corner fade in the red zone and you will see a much more productive offense for the Steelers.