After regularly tuning in to Seinfeld for the first time in about 15 years, I started to notice how much better it looks compared to either today's digital shows or the video-taped shows from the '70s and '80s. And sure enough, IMDb says it was shot on 35mm film stock.
It doesn't have video's fast frame rate which makes it look more like you're right there in the audience of a live play performance. The slower frame rate stylizes movement enough to distance you from the show's world. The lighting and colors also come out much better than on a typical sit-com from the '80s, which were shot on video.
And it wasn't only Seinfeld -- ER, Friends, Frasier, Murphy Brown, Law & Order, The Drew Carey Show, just to name the ones I checked. Some were still being video-taped if they were in the vein of the '80s sit-com, such as Roseanne and Home Improvement.
Perhaps that's one reason why some people respond best to TV shows of The Nineties (meaning, '93 and after). They probably didn't know it, but just sensed that they had better visual production put into them. Like me, you might not respond to some of them for reasons of tone -- wacky/zany, emo, glib, etc. -- but at least they are nice to look at.
During the 2000s, first it was all the game shows and reality shows that brought the video look back to mainstream TV. Reality-based content calls for greater photorealism in capturing motion, so video's high frame rate won out. Now even the comedies and dramas are leaving film for digital. The Big Bang Theory, about the only 21st-century sit-com to break into the top of the Nielsen ratings, started out on film but switched to digital.
Why didn't they care to shoot all the big shows on film in the '80s? (Some in the action genre were, like Magnum, P.I.) I think TV shows that looked film-y only appealed to audiences once the cocooning climate had set in. Since then the ideal has been to never leave the house. But they still want something cool-looking to watch for entertainment. If the small screen was the new big screen, then why not start shooting TV shows on film?