Source: I participated in building 3 apps (not all successful, but two made it to the app store/google play) using Cordova 3, and wrote an ebook on the Cordova CLI.
Moore's Law FTW.
When it comes to the question of what hybrid apps can or cannot do, Image processing is definitely something they can do. If the JS layer isn't fast or featureful enough for image processing, you can always drop down to native through Cordova plugins or something like ngCordova (http://ngcordova.com/). We always advocate full utilization of the platform, just like we would if you were building a node-webkit app.
I do agree that Hybrid is growing, and more people are finding it a good solution for what they need. That will only continue, and we hope to be helping them for years to come.
Maybe these aren't call Hybrid App Frameworks then? Is there a better term for frameworks like Cordova & Appcelrator?
The result is a highly rated app that's both fast and performant for the end user, while also cost/speed efficient for the business to run and maintain.