I didn't get a color TV until the mid-1970s so until the episodes reappeared on SciFi I never saw it in color. I absolutely agree that there is a lot more "spookiness" in the atmosphere when the episode is b/w. I understand why fans like the episodes in color, the costumes, etc. but it didn't take anything away from my enjoyment of the show when it ran on ABC.
I was surprised but impressed with directors who chose to film in b/w over color, like Paper Moon, Raging Bull & The Longest Day.