Costume design is a beautiful but precise art. One needs to understand the setting, time frame, and even the personality of the character that one is creating the clothing for. Although many laymen can look at an outfit and think "that belongs in the 1970s" it's much more nuanced than that.
Let's look at Jean-Pierre Dorléac, an award-winning costume designer who worked on many films and TV shows. His work is seen on Battlestar Galactica (1978), Buck Rogers (1979), Automan (1983), Airwolf (1984), and Quantum Leap (1989) among others.
Here are two examples.
To provide the look of the computer-generated hologram of Automan (Chuck Wagner), the costume was a unitard with adhesive panels of highly reflective material. A device called a beam splitter was attached to the camera to bounce the costume's reflection back into the camera lens, making it appear to glow. The blue starfield effect was added in post-production.
Each episode of Quantum Leap was set in a different time period, anywhere from mid-1950s to mid-1990s. All the costumes had to be commensurate with the setting. However the character of the observer Al (Dean Stockwell) was the exception. Even though he existed in the "present" of 1999, he had little regard for fashion and tended to have extremely outlandish combinations of clothing.
More often than not, the stars of the show get most of the accolades. Let's not forget the many people who work behind the scenes to make the stars look good, from costume designers to makeup artists.