BitTorrent / uTorrent, open source?

After the recent announcement by BitTorrent Inc that it has acquired the popular, lightweight Windows torrent client, µTorrent, there has been much speculation about the company making the source code of µTorrent public.

µTorrentBitTorrent Inc's official client is Open Source. Sadly, it is unpopular among users due to its bulky nature, and has lost market share to other, more lightweight and feature-full clients like µTorrent and Azureus. At one point, Azureus had many features that µTorrent could not boast of, but this has since changed and µTorrent is now a very feature-rich, and at the same time, small and lightweight program. People like it so much that they even go to great lengths to emulate it on Mac OS X and Linux.

Why would the company open source µTorrent?