Well, from purely an app developer's point of view, the situation with Webviews on Android is completely opposite to the one you describe! WebViews are power hogs and unbearably slow to render anything. Their only saving grace in that respect is that they share a common WebViewCore thread to perform most of the legwork behind the scenes, so you can have plenty of these with relatively low overhead, but they truly are to be avoided at all costs if your objective as a developer is low battery consumption and a responsive/fast UI.
The main problem with most android apps is that they still include a tiny WebView just for displaying ads, carrying with it its dreadful WebViewCore Rube Goldberg machine.
I find it sad that Android App developers in general are so poor that they can't figure out a way to make their apps run faster or smoother. Native is and always has been the way to go for performance, responsiveness, UI speed and power saving on those devices.
Here's to hoping that the Android team solves the horrible performance and compatibility issues on their Webview component so I can safely go back on my words in the future.