I felt the trilogy was no less Foundation-based than either Prelude or Forward had been. Besides, this way Daneel only has one "confidant"; why go back to the Empire and make up a new character when Hari already exists and makes more sense in this scenario?
But they didn't need
to use Daneel or Seldon! It's possible to write an excellent story in the Foundation universe without using Daneel and/or Seldon. Donald Kingsbury did it. Benford, Bear and Brin are great authors, among my favorites, and could've added greatly to the universe Asimov created, rather than edit it as they did.