Why isn't 80's design more popular?  

Grunge was real...but it was...
Grunge was real...but it was in part a rehash of previous efforts. Think mid to late 60's-70's rock and punk. Maybe even a dribble of early 80's post punk. Early 90's...good stuff. But died around 95 96. It left faster than it came. Grunge fashion remains to this day.
90's design...I've drawn a complete blank.
Hudson, the use of decades makes for a good summary. 10 year cycles as opposed 4-5 year cycles gives plenty of time for movements to come up and fade.

Yeah, 4-5 second cycles are...
Yeah, 4-5 second cycles are more the rage, rather than years these days, but the egg-timer is ticking, I hear, and most of us are poached.
By the way, I really liked Decade (released in 1977 or so) a lot back in the early 80s, the "definitive" Neil Young triple album retrospective, the lp with the guitar case covered in the around-the-world stickers.
And then Dylan came out with Infidels, I think around the fall of 1983, and shortly after, Empire Burlesque, spring of 1985 maybe, which the critics like to say sounds quite dated, both, of course, following his so-called religious period.
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Veering back toward the topic
Sidestepping 80s fashion and music for a moment, I'm not sure there's a lot of 80s product or furniture design trends we'd want to see again.
Do we really want Memphis in our homes? Half tantrum, half inside joke, even its progenitors admitted it was tacky.
Post Modernism is slightly less offensive, but doesn't exactly inspire passion.
The one bit of 80s design that does seem to have come roaring back is the work of Dieter Rams, which now comes to us in the form of everything Apple.

haha...4-5 seconds...
haha...4-5 seconds indeed.
Musically...the 80's saw the emergence of hip-hop onto the scene. By the 90's it was poised to become the cultural force we now see today. Not since Rock & Roll has there been a sweeping musical movement like hip hop.
The alternative music of the 90's, credit goes to 80's New Wave and Punk.
Oh...crazy 80's & 90s underground crazy creepy avant garde fashion... Leigh Bowery
80's brought us the home electronic revolution. Notably..home computers. Commodore 64, Atari, Nintendo, Intellivision, Apple, MS (?).
80's politics united a once divided country and freedom to millions...Germany.
80's film....no other film producer captured youth of the era more than John Hughes. Definitely affected my childhood.
80's architecture ...Michael Graves.
70's skateboard fad re-emerged in the 80's from Southern California's skate culture to be what it is today.
That's it. Need to cook dinner.

Poach, I think it was 50's 60...
Poach, I think it was 50's 60's Dieter that largely influenced Apple.
Good point on Post Modernism and Memphis. I also feel like Post Modernism & even Memphis was a re-evaluation of the Art Deco & Cubism movement.

What was big in the 1980's?
The Memphis scene. The High Tech industrial movement.
I thought the Memphis style was bordering on silly; highly decorative, but it doesn't seem like lasting forms.
The High Tech style was fun, and some of it has remained popular and classic (metro shelving, Pirelli rubber disc flooring, etc., but some of it seems dated nowadays.
The pop art 1960's stuff also seems dated too.
On the other hand, so much of the post war mid-century modern remains so classic, modern and timeless.
Perhaps some movements capture the imagination of generations after generations, and others seem to be dated of their narrow period.
(I can't imagine, for example, wanting a Marilyn Sofa and worrying about having to replace the foam rubber ever few years!)

A new slant
designers active life output example:M & L Vignellis work is it more 60s 70s 80s 90s... 2010?Parsons table form used from mid to late 20s to 2010 and beyond...height of popularity probably:1965 to 1975.Or think: early/mid /late 20th century.Vintage Memphis furniture is now a hard sell but the glass is more expensive than it was then.Memphis was an elitist thing for sure,Karl Lagerfelds Monte Carlo apt done up in it...

Right you are WoofWoof
I was thinking most specifically of the et66 calculator; but you're correct. Rams' consistent un-designed aesthetic certainly began much earlier.
I'm not convinced about the link between Memphis and Deco or Cubism. To me it's always seemed more rooted in Dadaism.

Memphis-Milano in the home
While appreciate the breadth and depth of the Memphis-Milano pictured for me it is too much. I enjoy having several pieces of Memphis-Milano furniture and lighting mixed with my collection of modern furniture and design. It is fun and full of color. Some of the ceramics also have a place from time to time displaying flowers or other objects (David Linley turned wood eggs). A little goes a long way.
I thought the Bruan ET55 calculator was designed by or at the very least with Dietrich Lubs. It was not the sole design work of Dieter Rams.

Believe it or not, there is...
Believe it or not, there is even today some resistance to non-modern USA design/decor/style from the 1980s, including one of the more predominant/popular trends of that time, called Country, which, as I recall showed up in many homes, modern and/or otherwise, during that period,: old rolling pins, Gunsmoke era coffee pots, pie cupboards with decorative punched tin elements ...
Which makes me wonder if a certain amount of what we call design/fashion, at least since the 80s, or before, doesn't have a little bit to do with resistance of the popular.

Of course, it appears that...
Of course, it appears that even resistance to the popular might be starting to become slightly en vogue around these parts, which is clearly good, far as I'm concerned, with regard to the likes of such godawful spectacles as American Idol and Rush Limbaugh, that ace of hearts kind of kneejerk mentality, at once passionate and unthinking as the current you-name-it USA flavor of the month or the Religious Right.
But what should happen then in those rare instances, say, when what's popular might actually be lurking in what's good, and vicey versey?
What's good?
It seems to me that the DA forum, when it peaks - and/or is occasionaly even at its worst - is often asking that great question, nonetheless.
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Resistance to the Popular
If resistance to the popular weren't part of Fashion, we'd have long ago reached an equilibrium where everyone agreed on what looked good. It's only the delayed negative feedback that keeps us oscillating between skinny jeans and baggy jeans, short skirts and long skirts, narrow ties and wide ties, etc.

Delayed negative feedback,...
Delayed negative feedback, yes, a saviour or sorts, or at least a dull corrective in light of a passion for immediate gratification.
Which could be one of several reasons why 80s
design/fashion isn't more popular.
Resistance might be great, resistance might be good.
Let us thank it for this food.
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Form v. Function
Maybe a lot of the negative reaction towards 80s Post Modern design, especially Memphis, is the "Form Following Function" issue. I think it was one of the motivations of Sottsass to challenge the idea of form having to follow function. Also the mix of ordinary material such as plastic laminates and more expensive materials on the same piece challenged established design concept. I like because it's been fun to collect over the years.
http://www.flickr.com/photos/memphis-milano

That's a great Memphis...
That's a great Memphis collection. Seriously. How is it to live with?
It seems to me, and I could be very wrong, a lot like a collection. And not entirely unlike a collection of rolling pins, Gunsmoke coffee pots, etc.
It doesn't seem, ultimately, as much like design as re-sign. And most of all, it doesn't, for whatever reason, seem alive. I don't mean to be a jerk. I like it too - as others here have said - in really small doses.