The title is rather self-descriptive, and call me crazy, but this is my favourite bit of music criticism of the year thus far. Kudos to Dave Holmes. It's not too often that the most insightful lines in a music article are consistently the funniest as well.
Breaking down the list further, we can see that the distribution of these 38 albums has been highly irregular:
1985-1989 (six albums, 44 weeks at #1)
Each of these albums was a cultural phenomenon and their core songs remain staples of "do you remember the 80's?" compilations up to the present day. Multiple songs from each of these soundtracks dominated pop radio at the time and each was responsible for making at least one or two careers. In the case of "Dirty Dancing", nearly everyone who appeared on it had a first or second career that they owe almost entirely to the soundtrack. There was even a "Dirty Dancing" tour, featuring the performers and music from the soundtrack, and an accompanying live album from the tour. And you thought this kind of brand-name cash-in started with the "American Idol" and "Glee" summer tours?
1990-1991 (zero albums)
Just like that, the soundtrack album gravy train dried up. It's not clear why -- were Vanilla Ice and MC Hammer really so invincible? The "Pretty Woman" movie and soundtrack were huge hits in 1990, and Roxette's "It Must Have Been Love" hit #1 on the pop charts, so maybe the lack of #1 soundtracks in these years is just a fluke, rather than a shifting of the guard, especially since ...
1992-1998 (sixteen albums, 72 weeks at #1)
Yep, soundtracks were back. There's no bunching happening here either, these albums are uniformly distributed over these six years. This works out to an average of four weeks at #1 per album, but that's misleading because six of them were in the top spot for just a single week, and four others were #1 for exactly two weeks. Most of the rest were mega-gigantic blockbuster hits with radio exposure to match, especially "Titanic" and "The Bodyguard". This is just further proof that although some people remember the 90's as a time when alt-rock and nu-metal were dominant, the truth is that sappy soundtrack ballads in the vein of Berlin's "Take My Breath Away" never went away, and were in fact bigger than ever.
I'm not sure what happened here, but I took a closer look at 1999, and it was a weird year for music. Teen pop, country, nu-metal, and hip-hop swapped in and out of the #1 album spot without any rhyme or reason. As for soundtracks, there was almost nothing of note. I suppose the most significant was the "Austin Powers II" soundtrack and it's radio hit, Madonna's "Beautiful Stranger" (Lenny Kravitz's "American Woman" also performed well).
2002-2003 (three, 10 weeks)
"8 Mile" was a phenomenon because Enimen was an unstoppable commercial force, and "O Brother Where Art Thou?" may have been the most unlikely Album of the Year Grammy winner ever, but otherwise you can't really say that soundtracks made any kind of comeback in these years.
Again, I can't find any notable soundtracks in these years. There were a lot of #1 albums in 2005 -- a majority of them spent only a single week at #1, so you know that soundtracks were ice cold if not a single one could ride a big opening weekend into a first week sales boost and a short stay at #1. The most notable soundtrack in these years would appear to be "Hustle and Flow" and its Oscar-winning track "It's Hard Out Here For a Pimp". Yeah, yeah, here's the link. Enjoy.
2006-2013 (twelve,17 weeks)
Soundtracks came back over night, thanks to Disney successfully targeting the tween demographic and young adult fiction making a jump to the big screen ("Hunger Games", "Twilight" saga). There were plenty of dead spots for soundtracks during these eight years, and most of these albums only spent one week at number one. Soundtracks were bankable but forgettable. None of these albums had a huge, breakthrough single.
2014 (one, 14 weeks)
"Frozen" gets its own category because no soundtrack has dominated the album charts like this "Titanic" in 1998. Every generation has its own Disney soundtrack to call its own I see.