Because it allows for proper prioritization of needs, allows for the better exploitation of our surroundings (as tool using animals), and is INCREDIBLY useful for helping us try to “model” other human’s behaviors and act as social animals as opposed to just being the regular kind.

Probably the most impact “Why” question probably started occurring before we were even human and it was “Why did they do that?”

Being able to understand the motivations of other beings is absolutely fucking incredibly overpowered both in terms of cooperative action with your fellows AND destructive action against foes/food sources.