We all knew from ANH that Leia was on a mission to bring Obi-Wan to Alderaan.
Now, in Rogue One we saw Mon asking Bail Organa to call "his jedi friend". Since Yoda always took a position of leadership both among the Jedi Order and among the Republic, shouldn't the Alliance have called for him, instead of Obi-Wan? Bail also knew that Yoda was in hiding, they meet together at the end of Episode III.
I realize that Yoda is in hiding so the Emperor and Vader would not feel his presence. Also, I know he said to Obi-Wan:
Yoda: Until the time is right disappear, we will.
Meaning they would stay in hiding until it was time to train Luke. But, since you are already going to call for a Jedi for help, why Obi-Wan and not Yoda? Or even both?