It's not a minor point; our hairlessness is a big reason why human civilization even exists. Without that natural insulation of fur covering us, we had to create clothing, and groups living in different areas produced varying levels of pigmentation to protect their exposed skin from the sun, leading to the development of our various races.
Oh, and the need to keep warm may have also contributed to our ancestors learning one other mildly important skill: making fire.
"Awesome! Let's throw some s**t on here and see what happens to it."
So how did we wind up as the hairless monkeys we are today?
We were filthy.
Yes, one leading theory is that we did such a horrible job keeping our fur clean, parasites became rampant. Particularly body lice we picked up from gorillas (don't judge, the Pleistocene period was a crazy, experimental time). So eventually, not having fur for the little bastards to nest in became an evolutionary advantage, and hairless offspring became the norm. It was certainly better than, you know, washing.
Bathing is for pussies.