As someone who is about to move onto book 2 of Kingmaker as a DM...
Intimidate will only be as necessary as your DM decides to make it. Frankly, as written Book 1 really only requires Knowledge (Nature), Perception, Swim, and Survival. Anything else is just gravy. I had to do a lot of tweaking to Book 1 to make something I thought would be really engaging to my players (and be something I actually was excited to DM).
So I'd actually say it's literally dependent on your DM. If your DM changes things to emphasize social interaction, then CHA.