Absolutely, and one of my favorite Trek characters overall. But it makes perfect sense. They had Spock, then came up with the idea of introducing his parents. Why was Spock the way he is? We know his mother is human and his father is Vulcan, so Spock's father had to be "extremely Vulcan" (whatever that means).
Spock was a pretty strict guy, and Nimoy played him brilliantly, as it was often clear that he was "acting" Vulcan, and always struggling internally to "be Vulcan". With Sarek, it was in his very nature. There was no acting involved, no inner struggle.