Well the deal with Java?
Java can run on many many many many many many many platforms, Mac, Windows, Linux, Sun etc.
Thats the benifit:
You just have to code one application and it runs everywhere.
If there was no Java LimeWire would had to be translated in the mac coding language (no idea which language it may be).

When LimeWire crashes its not Java's fault but the programmers
(No offense, LimeWire Team ).

Or maybe you should get the newest Java Runtime.