If there were a byte-code available you can bet people would be using other languages. ASM.js exists, and many languages compile to js at the moment.
As for PHP, lots of people still eat at McDonalds. I can't explain why.
I think a more apt analogy would be: no furnace to forge your own cooking utensils (hour long build from source to get latest and greatest [7.8] installed) which you use to prepare the meals (wait for your application to compile) that you then stuff into your mouth (deploy to server).
Basically, you can get yourself access to a furnace to forge your own melon baller, but you've already got a spoon, and someone else will be shipping you a melon baller next month.
Not sure what you mean by this - I guess you're assuming the "client system" is always a web browser?
Currently, I'm writing code for a piece of middleware that is a client to a server that models networking equipment. This client then pushes hundreds of thousands of responses into a fast message queue. None of this is written in JS.