Shaw said:
What I would add to that is that television of the sixties and seventies (including dramas) were played out more like stage productions. Everything that could be over done was done to make up for everything that was lacking in production values.
Today we expect to see hard edged, ultra life-like presentations on television.
And in a similar way, the very colorful look of Trek was important to show off color televisions back then.
Actually, this is also a matter of perspective.
The production values were quite high for the show, as well as many others on TV at the time, which is why so much was filmed on sets rather than location. Location shooting in the 50s and 60s was generally a sign of a lack of budget to build sets, though that would change when "avant garde" films like "Blow Up" came along and the studio system began to die out and profit margins became more and more important.
The shows were not just colorful because of TV but because technicolor was popular in movies, and TV basically was a poor man's version of movies, which were a poor man's version of theater. Ironically, as TV became more popular, movies had to change to differentiate themselves from TV shows, so in addition to changes in film stock, movies gained a harder look (some might say more realistic), let characters cuss, showed nudity and sexuality, and amped up the violence, which were ways to compete against TV with what it could not show. The quality of the acting was on par with anything of the day -- most people tuned in to see a
performance, not to see someone go the method actor route and try to seem like just a regular person in a ridiculously extreme situation.
Today's shows will seem equally as silly in future -- watch "CSI: Miami," for instance, with its self-indulgent acting from David Caruso, bland acting from everyone else, comedy-club-styled lighting, and two-instrument soundtrack. Styles change, as do tastes and viewers.