Native apps with JavaScript? Give me a break. The only "Native" apps worth writing in JavaScript are web apps. Thank you coming out Nativescript - pack a lunch.
Cross-platform compatibility is a genuine problem and Nativescript attempts to solve it, just like Titanium, Ionic, and React JS (which is used in production for Facebook Groups).
Write/learn once deploy anywhere is valuable to a lot of people. If you don't like it that's fine because there's no singular best solution and the tradeoffs don't appeal to you. But they at least deserve your respect for trying.
Whoever eventually delivers a viable offering will clean up in the corporate apps market. Companies have lower expectations for internal apps and don't want to hire Java and Swift developers to create each.
Companies who have such low expectations already have alternatives in the form of a WebView with extra bells and whistles, like cordova or any of the numerous JS-based native-but-not-really frameworks and libraries. This is just one more among many, many similar alternatives.
Write/learn once deploy anywhere is valuable to a lot of people. If you don't like it that's fine because there's no singular best solution and the tradeoffs don't appeal to you. But they at least deserve your respect for trying.