I think the issue with Java has been with applets that are able to escape the sandbox. In other words, with running apps you don't quite trust. That's not an is

I think the issue with Java has been with applets that are able to escape the sandbox. In other words, with running apps you don't quite trust. That's not an issue here: you are implicitly trusting the browser itself, just like you trust firefox. So in my opinion, Java isn't inherently worse than a lower level language. (I'm not 100% convinced it's better, though.)