"Whoosh," is the sound you hear over your head. What's the point of Java?
You really do *not* want the honest answer to this question, but I will give it to you anyway: So people who would otherwise be employed asking "Would you like fries with that?" can get non-performance critical programming jobs.
Why do people use it vs why do people use C/C++ vs. Java? Sometimes you need to be closer to hardware. This is one of those times. Therefore, you wouldn't use Java.
You *always* have to be closer to the hardware:
#1: Almost everything is a mobile device these days; people buy laptops instead of desktops, cell phones music players, etc.. The closer you are to the hardware, the better your battery life, the lower power your processor can be to do the same amount of work, the cheaper the unit price for the lower powered hardware and smaller battery, the lower the cooling system costs (mostly, you can go without them, or operate them on "low"), etc., etc..
#2: Being closer to the hardware lets you reduce the number of blades/servers/PaaS instances that you require in your data center or cloud. This reduces costs, again in terms of cooling, but also in rack space, and power requirements. Facebook rewrote their PHP code to be compiled to binary code, and it saved them over 50% in servers. When you are a startup, and have tons of VC money to throw hardware at a problem, you can get away with not having to worry about those things, but when it's time to get to scale, they start to become major issues.
You can *get away* with not being closer to the hardware... for a *short time*, when you are engaged in rapid churn (e.g. new web UI ever 2 hours), or doing a lot of rewrites or running on hardware that better than the hardware you intend to deploy on, but after that being closer to the hardware is *the overriding thing*.