Looking at all the 90s prime time soaps, its not hard to see why they failed to launch, even if they did have a good premise and storyline, with the start exception of BH 90210 & Melrose Place, both of which ran for most of pretty much the entire 90s decade with BH 90210, just making it into the first few months of the Noughties, however I'll get to reason as to why those shows were successful in a moment.
The prime time soap genre had reached saturation peak point by the middle of the previous decade, by 1986 all four of the major prime time soaps of the era (DALLAS, KNOTS LANDING, DYNASTY & FALCON'S CREST) beginning fall in popularity,
Dallas, Dynasty and FC had all ended within a year of one another between the years 1989 to 1991, only Knots Landing continued to stride well into the mid 1990s (though the years 1990-94 did seem slightly more 80s hangover) but that was because it was structured around a middle class community with several families rather than based around a singular wealthy upper class family as with the other three.
And this was probably why BH 90210 and MP were successful, it focused primarily on teens and twentysomethings, a demographic the 80s soaps never really focused on, plus both shows were set in a community, okay the Walsh family on 90210 were the main family for the shows early years, but this quickly changed.
Prime time soaps in the 00s were probably more successful than their 90s counterparts because, enough time had passed between the final episode of Dallas and the first episode of Desperate Housewives for instances, in order for the genre to be revived somewhat, also 90s soaps were often branded as a "drama serial" when we all knew that it was still cola with a Pepsi label on it.