Let us add stories to Storytime... I agree, we definitely need more to choose from.

The StoryTime! application is key to maintain a successful ongoing user. For those of us that have Facebook Portal's to connect with far away grandchildren. The older kids - teens - will, perhaps, sit on a portal call for a couple minute with the whole family. However, they will generally use their own devices to FaceTime or Video chat if they really want to schmooze.
SO...who is the target audience? The 1-8 year olds on one end and the grandparent on the other. Young children do like the repetitive nature of reading the same books over and over...grandparents DO NOT.
I know that many people dont like when they have to "pay" to get access to content after they have already purchased a device...however, if the library that is already available remained "included with purchase" there would be plenty of options for one to see if spending additional money was "worth it" for that individual's needs. For those of us that use Facebook Portal multiple times a day it would be the single MOST worth it purchase.
It is extremely difficult to maintain a conversation with a 2 year old. Grandparents can maybe get one or two minutes of their attention. It is awesome that the camera follows those little people around the room as they play or show us their new-found skill of tumbling!
With StoryTime! we can interact for 20-30 minutes! We can experience their growth in predictive comments, kvell in their ability to remember where the "plot" is headed next, and soak up the adorable animal sounds that coincide with the correct animals!

I know that creating the interactive video story content is time-and money-consuming. Perhaps adding already established children book content Apps, such as Epic!, Bookful, or Skybrary. All of those have some free content, as well as, paid content. Or even putting the kindle children's books...with the ability for both end users to be able to open and use/read to the other.