I think the biggest 70's pop cultural holdover in the 80's was television. Not everything, but looking back, a decent amount of tv music/set design/graphic design still seemed kind of 70's throughout much of the decade.

I believe that TV is generally the popular medium that is the slowest to "get with the times," since the creative work behind popular television, unlike popular music, is usually done by people whose era of being receptive to new trends and innovating such trends has already passed.

I will let TV Tropes (http://tvtropes.org/pmwiki/pmwiki.php/Main/TwoDecadesBehind) speak for me:

happens because TV writers tend to be busiest in their late 30s and early 40s, and (like everyone else) their tastes and preferences were formed in their teens and early 20s; by the time they reach the big time, what they think is fresh and modern is actually 20 years out of date. Author Appeal and a desire to Write What You Know also plays an important part. This is closely related to the fact that such franchises as Transformers, Teenage Mutant Ninja Turtles, and Masters of the Universe are getting revamped ~20 years after the peaks of their popularity; in fact, G.I. Joe: The Rise of Cobra (2009) was a revival of G.I. Joe: A Real American Hero from the 1980s, which was, in turn, a revamp of the original Joes from the 1960s.

In light of that, I think that what you have said, Todd, makes a lot of sense not only for the 80's television (with regard to the 70's), but perhaps any decade's television with regard to that of the previous decade (or decades, if you go by the idea of the page I linked to).