I should add to the post below that I when I think about darkrooms, I think about black-and-white. I would never consider a darkroom again if my intent were to make fine color prints (I happen to find B&W more appealing, but that's my personal taste). Carl Weese said in about 1999 that black-and-white was perfect as it was, but digital represented the true coming of age of color; with apologies to the several excellent traditional color photographer/printers I know, I concur. For me, the darkroom would be for monochrome; for color work, it's the computer all the way.
A computer workstation is much smaller, much more portable, and can be used out in the light, where people congregate. Naturally this negates what for some of us is an advantage of the darkroom—its function as a sanctuary, away from interruptions and from other obligations. But there are good reasons to want to be around people apart from being sociable. George Tice reportedly had a picture-window in his darkroom (covered in rubylith of course) that looked out on his children's playroom, so he could work and babysit at the same time.
Not only is the darkroom a problem during the years when one's children are small and need room and attention themselves, but, as many people in the comments have cumulatively noted, what Nick Hartmann calls "the room-sized accessory" is problematic as one charts a course through life, too. Americans might typically live in a house when they're young (their parents'), and a house when they're older (their own), but the years in the middle there can be more provisional in terms of living arrangements: dorms, followed by apartments, usually, with frequent uprootings. What this means in practice is that, for many people, their participation in darkroom activities is fractured as they go through life. At the darkroom magazine where I worked, I used the term "re-entry photographer" for the hobbyist who was rekindling, in retirement, an earlier interest in photography. The category was a significant segment of the readership (it kept the average subscriber age remarkably high, too).
In fact, the popularity of darkrooms initially had to do with the rise of home ownership in this country after WWII. To have a darkroom meant you had the space to devote to it; it usually implied that you had a habitable basement, which in turn implied that you belonged to that expanding class of arriviste, the homeowner. Part of the status of having a darkroom was that you usually had to have space to burn in order to have one.
The peak of the darkroom as a home hobby in the U.S. occurred in 1979, indicated by a peak in enlarger sales and in the circulations of darkroom hobby publications. The first big contraction came during the Gulf War. The second, more protracted (and more extreme) has taken place over the last 15 years, especially during the years from 2000 to 2005, as traditional wet processes were replaced by digital cameras and inkjet printers. By the mid-to-late '90s, the sales of enlargers, once a robust industry, had fallen such that the entire industry was selling considerably less than Beseler once sold all by itself. Today, annual worldwide sales of new enlargers of all brands is probably in the mid- to high hundreds, or less than 1% of what it once was.
Of course, one thing this has meant is that darkroom work is a much more exclusive activity these days. It's a much smaller club, but the people who have stuck with it tend to be passionate, involved, and quite skilled and knowledgable. In addition, we know much more about how to do fine work now than we did even as recently as the peak, thirty years ago. Certainly the average level of craftsmanship among darkroom workers is far higher now than it ever was when so many people were dabbling in it.
There are far fewer professionals now, but contrary to common belief, amateur status is just as often a determinant of quality as a lack of it. A pro gets very good at working fast, but efficiency is closely tied to the bottom line, so excessive time and care simply can't be lavished on any one print. Amateurs run the risk of working so little and so infrequently that they never get their skills in decent shape, but they also have the luxury of being able to put a lot of time and careful judgement into each print. Pros make good prints, but the very best prints (as well as the worst, I would imagine) tend to be produced by artists and amateurs.
Over the two decades from 1980 to 2000, I worked in many darkrooms (twelve, to be precise—I just counted 'em up), and more of them than not were highly provisional: only a few of mine were plumbed, and one, in a "vintage" apartment in Chicago, was a kitchen. ("Vintage" in real-estate-speak means "old and unrenovated.") The two best ones were owned by Paul Kennedy, one in his pro studio and the other in his basement, which we built after Paul realized he could do 90% of his non-location work in his garage and forego the heavy monthly studio rent. One of my darkrooms, but only one, was so cramped and primitive as to be essentially unusable even for me. And I can do good work in pretty primitive conditions.
Despite the idealized, heavily equipped darkrooms that are shown in how-to books, a great darkroom can actually be very simple. If I find time, I'll go into some particulars later in the week.
Featured Comment by Dennis: "So I stopped in Best Buy today at lunch time, breezed through the digital cameras on my way to the computer section, then on my way out the door had to do a double take as there was a big rack of new...vinyl albums. Yup. Saw these thin square packages that looked like albums and figured it was retro packaging for something else, but no...there was a sign saying to stop by aisle one of the music section for more vinyl.
"Sounds like someone didn't get the memo.
"Or maybe in another ten years there will be a similar display featuring film and film cameras."