He was so fucking concerned about optics

To be fair the media went apeshit because he wore a tan suit and used mustard on a sandwich!
With Trump it's like: "Oh and Trump sexually assaults women willy-nilly because he thinks he is entitled to it. But that's OK because that's just who he is."

If Obama had pushed for Trump to be arrested and accused on treason, USA might have ended up in civil war.
That task was not for Obama to do, it was for the judicial and security services. And yes they failed, possibly because security services are generally overwhelmingly right wing.

That said, I would have loved to see Trump in an Orange jump suit, he 100% deserves to be imprisoned for the rest of his life.