I guess this is our super saiyan transformation. With the death (?) of an ally as a bonus for more sadness.
For me, the problem with this fight, is that there's no introduction, nothing to induce it, no clue, it just jumps on us. And the worst is the forced drama that comes with it.
I'll take DBZ as an example because that's my favorite shounen, but before the fight with Freeza, we were clued on how powerful he was, there was a slow build up before that final and dramatic battle on Namek.
Here, it feels like Goku fighting king Piccolo just after having met Bulma and before he finds the second or third dragon ball. You need to let things marinate, dude. It's too much, too soon.