A great Story Map is actually really hard to create. Great Story Maps are require rich media, high resolution images, thoughtful and visually engaging maps and more. One of the areas where one can spend a lot of time working on a Story Map is hunting down great pictures. It gets even more difficult if you need or want royalty-free images released under a Creative Commons license. Google Image Search has some filters for this but honestly its like searching for a needle in a haystack.
There are several great sites for obtaining great royalty free stock photographs though. Unsplash, StockSnap.io, Pexels, Burst and Pixabay are the ones I can think of off the top of my head.
Currently, I have to go hunt down photographs, either download them and then upload them somewhere else to be hosted, or host them in ArcGIS Online, and then properly attribute them in my Story Map.
It would be fantastic if Esri worked with a couple of these companies to create an integration for Story Maps so that I could seamlessly search for stock photography from these sites right within the Story Map builder, and add them to my Story Map sections with attribution, if neccesary. The attribution could work similarly to the way that Basemap attribution works. Just some small overlay text in the bottom-right corner.
Certainly, I think this would make the creation of great Story Maps a lot easier and we could spend a little less time hunting for and integrating imagery and more time on producing something awesome and inspiring.