I believe [AS] has live action shows now, not just as a means of change and showing something new, but because the live action shows that they have or have had tend to fit look and feel of the network, and/or the sense of humor. Tim and Eric and The Mighty Boosh, a new show that's on it's way, really have that colorful, strange, and surreal look that's dominant among Adult Swim's shows. Delocated has the kind of awkward, improvisational humor that dates back to Home Movies.
I can't explain why else they'd be picking up more and more live-action shows, and less animation. There is the fact though, that they're faster, easier, and cheaper to produce. I know that's a terrible reason, but [AS] doesn't have a huge budget, and a lot of their animated shows have huge, long production periods - a year, if not more, for just ten episodes. I think that's why they're trying to fill the gaps with a ton of new, faster shows. Animation isn't really honored any more, though it really should be. And, in a way, that is what [AS] is about. It's for adults that still enjoy the magic of cartoons. Though that's fading fast, I think Superjail! is representative that [AS] hasn't completely lost its ways, so it's no wonder that show got so wildly popular so fast.
I must stress the point though, that shows shouldn't be completely cast off just because they're not animated. Tim and Eric and Tom Goes to Mayor are great examples of shows that managed to mix animation and live-action in a totally creative and effective way. Delocated, too, would probably be less effective as a cartoon, because of the premise and the humor. But yeah, a lot of the [AS] live-action shows certainly find ways to push the limits of reality, like any cartoon. Likewise, a lot of cartoons find ways to be depressingly realistic.
Oh, and Important Things with Demetri Martin undoubtably belongs on [AS], and I do hope they buy it or something. Few shows have lasted very long on Comedy Central.