I don't know if it is out of pure minimalism or pure laziness, but I see more and more rock drummers using only one cymbal (in addition to hi-hats) on their kits. Usually, it's just a ride cymbal. To my fellow drummers, I think this is too minimal.
Some explanation for non-drummers: drumsets are usually outfitted with a 16"-18" cymbal (called a "crash") that have a rather high pitch when hit. A ride cymbal, usually 20"-24" in diameter, has a deeper, penetrating pitch when struck.
For a band like the Flaming Lips, whose material is rich in melodies and orchestration, the drums work best when they are minimally set up. Drummer Steven Drozd pounds his drums and his ride with big, simple beats, thus allowing the guitars, pianos, strings and everything else some room to breathe.
But what about all those bands that don't have that many colors in their sound? This is where I throw a flag. I often see this approach in a lot of these newer, garage-y bands. Sure, it's cool to see a band rocking out in that vein, but seeing a drummer confined to one deep, crashing sound is frustrating.
You need color in your sound and that includes the drums. I'm not saying that I long for the days of kits with ten crashes, four hi-hats, three chinas, two rides and a gong. Just a couple of crashes, in addition to a ride, works in a variety of ways with a variety of music.