But Underworld have always been pioneers of the "never done before". They were letting you download Kittens online before Napster was even a word. They released a cutting-edge, forward-thinking live concert DVD (there's a great article about that
here).
And it's definitely a plan to get around the problem of illegal downloads. The old way of the music industry is broken. Album, single, tour, album, single, tour ain't gonna cut it anymore. In the online digital age you have to get creative with the way you market, release, and monetize your music. Underworld have already taken steps towards that with they way they've released their music online for purchase and through their website and radio shows.
My musings above were borne out of the thought of how to do an album release in the current music industry climate. The "free album" thing has been done to death already, from Radiohead to Nine Inch Nails. They released albums for little to no charge and then later monetized it with a physical release or even super-deluxe-packaging releases. So, in thinking about how to do it differently, I figured why not combine the paid release with the free stuff. You have the standard album release, but now you have even more! New, free stuff. Stuff packaged differently and distributed in a way that wouldn't make sense in a physical package, yet complements or extends the original physical release. The online RiverRun EP's, of course, fit this bill perfectly, so it just made sense to combine it in some way with a physical album.