Will we ever watch most of the deleted Joker's scenes from the trailers?

I don't know if we will ever watch most of the deleted Joker's scenes from the trailers.

There was a scene that I would really love to see in which the Joker throws a grenade and say bye bye.

But I read that scene is when the Joker interacts with the Suicide Squad. If that is the case, how would they explain the cut of that scene if that is the only time the Joker interacts with the squad and intervene in the main plot?

Why did they change the scene from the first trailer? People liked that scene and the way Jared said " I will hurt you really really bad" and then gave that typical wide Joker's smile. So why the hell did they change it?

Most of the cool scenes that appeared on the trailers, they deleted or changed it. Why?

It seems that they made on purpose and selected the worst takes of each scene they filmed.