What's the purpose of self destruct?

I've started playing Nier: Automata for the first time (no spoilers) and I'm overwhelmed by a lot of the small features in the game.

One of the features I can't quite figure out is why I would self destruct. It doesn't seem to fill a role in combat as the 1hp your character is left, the long activation time, and the huge movement penalty afterwards which are an immense offset compared to the damage you might deal to an enemy.

As you said, self-destruct does not have much practical purpose while in combat while playing as 2B and 9S.

However, playing as A2 in route C (using the same button combo) triggers Berserker mode rather than self-destruct, which does give you some edge while in combat.

Aside from that, there are two trophies related to the self-destruct feature.

Trophy 1

Since self destructing destroys the pants, there is a trophy for playing as 9S while in his underwear for a total of 1 hour.

Trophy 2

NieR:Automata has a total of 26 endings. 21 joke endings and 5 true endings. To get one of the joke endings is to self-destruct while in the Bunker.

It has none. As you have experimented it's pretty unviable in battle, and probably useless since I don't believe it does a decent damage to enemies, also leaving you in a critical situation.

It's that kind of feature in Yoko Taro's style. When 2B or 9S try to self-destruct they just remain in underwear. So don't think it as a last resort move, but more like something for... nice visuals when the time comes.

Doing so will also help you get a trophy titled "What are you doing?", probably pun intended.

A better application of self-destruct is when using 9S:

After taking over a robot, you can self destruct to do massive damage to surrounding enemies without the negatives of actual self destruction