I thought it was becuase of the "one loner" theme (which they had in the voiceover at the start of some of the earlier episodes). Meaning, he was always ultimately alone. "One man can make a difference." Meaning one man, alone, without a woman by his side. Just a machine, the car. Actually, I read that originally the show was to focus mostly on KITT, the car as the center of the show.
I would have probably liked it if KITT grew 'fond' of some of the ladies on their mission or at least Bonnie, in a way that he's close emotionally with them in some computerized form, as if to establish he's more sentient than they had originally realized (maybe could have wrote this in the later seasons). Give it a new twist, something different. But I did like the car/driver protectiveness relationship though, nonetheless. Car enthusiasts like myself can pick up on that and appreciate that.
I also liked some of the humor that was between Michael and KITT regarding Michael's escapades with the ladies.
And every time I hear KITT say "I've heard that
one before." I just have to laugh.