One thing to remember is that with Star Trek, TNG, is that the only real competitors was live sports and what the Major broadcasts networks had on.
For example, in 1990, in my market even if you had Basic cable you had
Major Broadcast Networks: ABC, NBC, CBS, FOX
Sports: ESPN and TBS (TBS main feature was that it showed Atlanta Braves Games and reruns)
A few cable channels, which consisted of reruns of old shows and perhaps nature documentaries.
"Independent" Channels - On my area it was WJZY (which turned off at midnight!!) and a Chicago broadcaster (wgn I think)
And a few assorted channels like the Home Shopping network.
The Independent channels would buy both reruns of stuff that was on broadcast TV, but also first run syndication, which in 1990 or so was Baywatch (Babewatch) and Star Trek, TNG.
Thus, MANY people would click though the TV, see that Star Trek TNG was on, and sit and watch it. Or they would sit there kids in front of Star Trek TNG as they knew it would be kid safe and wholesome.
Just a few year later in say, 1994 many of those Non-network stations had signed up on to one of the new networks (Which eventually merged into the CW.) and the whole idea of producing a expensive show for first run syndication died. In addition, the number of cable channels doubled and then tripled, balkenizing TV viewership.
So for example, almost EVERYONE knew who Picard, Data, Worf, The Borg, and so on where. Even my friends who HATE SF will have fond memories of Data.
By the time DS9 rolled around, the market was fracturing. Heck, out of all the Syndication shows out there, only DS9, Xena, and Babylon 5 really survived (Babylon 5 survived the ending of its "syndication network" IIRC)