I also think Obi-Wan need to be unsure and shaky as a master and constantly looking up to a person for guidance who is no longer with him. Qui-gon is the master Obi-Wan wants to be.

I don't know, I think it would be nice to see Qui-Gonn turning under the influence of Tyrannus during episode 2. After all he is a bit of of a rebel among the Jedi.

It would had a conflict for Obi-Wan between staying true to the Jedi code, on Yoda's side, and becoming a part of the separatists with Qui-Gonn (you know the deleted scene of AOTC where Dooku/Tyrannus tells him that the Republic is under the influence of Sidous). That way it could make sens that Obi tells Luke that Yoda was the master who trained him, because he was on Yoda's side during the Clone Wars and he don't forgive Qui-Gonn what he did.