As before, Pandora is betting that the podcast version of its Genome Project recommendation system will reel in show creators. You may be more likely to subscribe to a podcast if you're drawn in by a special guest or hot topic. Of course, it also helps that Pandora has about 64 million monthly active users at last check. While the user base won't compare to Apple or Spotify, it still amounts a lot of potential listeners.
This is also about keeping up with the heavyweights. Apple and Spotify in particular have touted podcasts as important parts of their audio libraries. If Pandora didn't follow suit, it might lose customers who want all their listening to come from a single provider.