I've had to program in Java, and I've chosen to program in Perl. I have done graphical Java, simple command line classes, and J2EE. I have built blackjack systems, encryptions systems, telecom switch activation, and basica database construction/manipulation scripts - all in Java.

In Perl I have done a lot of financial analysis and fun little projects.

If I want to program something quickly, then I use Perl. If I want something that is OO and very easy, and speed isn't essential, but I still want it faster than Perl - then I go to Java (or if I want a UI). If I want something and speed is all I care about - then C.

I personally have no issues with Java, and I certainly enjoy Perl - I don't see how one has to be better/worse than the other - so I guess in the end I agree with your point in that there is no reason to use one language for everything.

That said, JavaScript is the way everything should really be done - pure power right there.