Sure, but look at the future a bit. I highly doubt iOS will ever run Java and I highly doubt Android will ever run C#. But hardware will get faster, and as that

Sure, but look at the future a bit. I highly doubt iOS will ever run Java and I highly doubt Android will ever run C#. But hardware will get faster, and as that happens the demos performance will improve. It may be a bit early to write 3D games or video editing software in JavaScript for iOS and Android and Windows all at the same time, so you've got to look to the future for that kind of excitement.