His mind wasn't changed before he went to see the Hokage. If it was, he wouldn't had told them that he was going to destroy the village would he? If he changed his mind before meeting them, then there would be no need for him to say that.If his mind wasn't changed he wouldn't have seen the hokage in the first place so yes his mind was changed. Then after talking to the hokages now he wants to become hokage change number two. It's wishy washy and he is not complex like you said kill and destroy are the fundamental ideas of his till now. Very easy to foresee his actions.
Again, he's only changed his mind once and that was after speaking to the Kages. That's not wishy-washy at all.
You said he changes his mind too much and only point out two moments? One which he didn't actually change his mind and one when he did?
It doesn't destroy any of his fundamental ideas because he has completed 2 of his original 3 goals.
If he's easy to foresee, then I guess you knew he was going to take out Orochimaru?
You knew he would kill those samurais?
You knew he would pierce Karin?
You knew he would decide to become Hokage?
You knew all that? Yeah, I'm not believing that.........
Like I said, he's not one-dimensional and the "good guy" so you think he hasn't developed well as a character.........