This is not a bad flashback as it is building to something more, but Kishi can't let this drag out anymore. But it seems like a pivotal flashback as the climax of the story is approaching or has been reached already.
I too would like to see Naruto surpass his predecessors in other ways then just more powerups. Having Sasuke fight with him to take down Madara and Obito seems reasonable. But I don't think Sasuke will be convinced all that much from Hashirama's story. I will say that Sasuke, unlike other Uchiha has an isolated upbringing so that makes him unique as a lone wolf or a wild card.