That's one of the best things about digital media: the picture and sound quality don't fade. Vinyl records wear their sound quality down with every play. Video tape loses image sharpness just from the passage of time, no matter how it's stored; this is due to entropy at the molecular level, and losses vary a lot from tape to tape. I've heard of at one case of a vintage sitcom that could not be put out on DVD because the tapes were so degraded, but I can't recall the title.
I think you are thinking of
Alf, as it was shot on videotape, however, except for one DVD release here in Canada, the Season sets all used the Syndication masters, rather than the network masters. Alien Productions claimed that the network masters were in terrible shape and that the syndicated versions had been kept in better shape. But from what I’ve seen of the Canadian DVD, that claim is highly skeptical. Out of the 3 episodes on the set (all 3 were hour-long specials) only one showed any sign of issues, and that was a very brief dropout during the end credits of the “Tonight, Tonight” show (and it was only a pixel wide).
However, next to film, tape is still the best way to store video and audio for long-term storage, as people are still able to get video from old tapes. The oldest known videotaped American program is the October 13, 1957 broadcast of “The Edsel Show”
Also videotape can hold large amounts of data. The majority of TV stations broadcasting now are still using digital videotape as those tapes are cheap to use, long lasting and reliable, vs solid state media and hard drives that are more expensive and are not as reliable as tape.
Brightness, contrast, color saturation and whatnot are all mastering decisions made when the Blu-rays were authored.
Those are all done during the transfer step, since by the mastering stage, your brightness, sharpness and color saturation are already locked into your video. You can tweak it a little bit, but if you transferred it to bright or too soft, you can end up with something that looks like a lot of those Public Domain films where you have no detail in the image and only the outline of the actor, or the “Flintstones A Christmas Carol” where it looks like the telecine camera was out of focus, so across every format (broadcast, VHS, DVD, digital file) the special is extremely soft.