. . . As part of its mission, TOS was supposed to get more people to buy color TV sets. I think there was even a business deal between NBC and RCA, but I'm vague on that.
RCA is the parent company of NBC.
IMHO, the original Enterprise
bridge is still one of the most practical, functional and believable sets ever created for a sci-fi film or TV production. And, while the TOS Engineering set may not look "real," at least it doesn't look like a beer factory.
Sure, the look of Trek TOS is dated in the way that everything becomes dated. But it also has a timeless quality, in no small part because of the deliberate minimalism of its set design. This piece
has been referenced here before, but it's worth another read.