The Good Natured trait is so popular because it subtracts 5 points from the four combat skills- Guns, Melee, Energy and Explosives- of which a character typically only uses one, and invests them into four non-combat skills- Speech, Medicine, Repair and Barter- all of which are at least somewhat useful for every character. Once you've invested 5 points into the combat skill you use, you're left with 15 free skill points.
However, suppose I want a Guns-centered character to take the Cowboy perk. The requirements for Cowboy are Guns 45, Melee 45, which means that you're going to have to invest in Melee. The skill books for melee are all VERY far into the game, and even with them you still don't reach 45 Melee. Which means that if you took Good Natured you're left with only 10 "free" points- in which case, is it worthwhile compared to other traits you could take? Cowboy guns are usually very durable (and reliable when below optimal condition), and they mitigate the downside of Built to Destroy extremely well; their spread is low so Fast Shot doesn't hurt accuracy too much, etc. So, how worthwhile is Good Natured to a Cowboy?