I previously asked this question for iOS 7. I am on iOS 8 now and in the Settings for Touch ID, there is a specific toggle for
Use Touch ID for iTunes & App Store.
I turn it on - it tells me that I need to create a passcode (in case Touch ID isn't available). After that, it makes me enter the passcode to unlock the phone.
Is there a way to use Touch ID exclusively for the iTunes and App Store and also not having a passcode on the device?