Java on the Mac is malware by design. It bypasses the entire security infrastructure of OS X. It's worse than Flash, and Flash is plenty bad.
There aren't many apps that really need it, and most of those have solid Mac alternatives. (Sorry Minecraft fans.)
The problem is corporations. They use VPN products that require Java. (Way to go corporate America -- mandate use of a security product that dramatically reduces network security. Alas, this is so typical.)
So many of us can't go entirely Java free until that problem is fixed.
So we need an app.
An app that disables or enables Java just when we need it. (Ok, Minecraft fans, just for gaming purposes.). An app that only Admin users can run because it needs Root privileges.
Maybe it changes privileges on the Java executable. Maybe it renames it. Whatever, it makes it NOT work, OR work, in a way that Admin users control for an entire machine.
Ideally Apple will provide this, but they might not. Apple, correctly, wants Java on Mac dead.
This would make a great utility. $20 bucks? No problem. I don't see any reason why it couldn't meet Apple's App Store requirements.