But C/C++ are difficult to use (I'm sorry, "challenging"), error-prone and crufty. Luckily it is possible to have high performance, memory safety, ease-of-use and pretty much everything else you might want in a single language. A subset of that language could be used for systems programming, and the "full" language could be used for everything else. AFAIK there is no single language that has everything today (high performance, scriptable, memory-efficient, scalable, easy to learn and use...), but there are pretty good languages like D, Julia and Nimrod that combine a ton of good things, and some of these languages (D, Rust) can be used for systems programming. So far there isn't one "perfect" language that I can point to that would be great for kernels and scripting and web apps and server apps, but I can certainly imagine such a language. Until we nail down what an ideal language looks like, why not build a VM that can run the wide variety of new languages that being created, something that works equally well for web pages and offline apps? Why, in other words, should only Google and Mozilla be in charge of the set of languages that run in a browser?
If Microsoft had done everything right, we'd probably still be locked into proprietary MS Windows. Their mistakes in the short term will probably lead to a healthy heterogeneous ecosystem in the long term... but in the short term, I am disappointed by browsers (why do you force me to use JS?) and with Android/iOS which were not really intended to compete with Windows in the first place).