How can I rate Apple's Podcast.app in the iTunes App Store?
From what I have been able to gather, it looks like the Podcasts App and the iBooks app are the only apps made by Apple that don't have a ratings button. I am guessing since the Podcasts app (and iBooks) are automatically installed on your iPhone or iPad in iOS 8, and are also installable from the app store on earlier versions of iOS, they most likely just omitted it because you can't delete them in iOS 8. Just like you can't rate Apps like Messages or Phone on your iPhone.