Ironically, the three languages you listed - Java, C#, and Objective-C are all available on all major platforms. I could write code in any of those languages and have it run on
- Windows
- MacOS
- Linux
- Android
- iOS
Furthermore, the apps would all be native. That closest Javascript can come is to use the uncanny-valley of HTML5 without native widgets or performance.Frankly, Given that the burden of learning a new language is tiny, I see no reason why we should try and cram Javascript into every nook and cranny. It's a fairly mediocre language at best.
tl;dr The three languages you listed are all capable of better cross platform support than Javascript.