I think Eclipse is still on 3.3 or something in the main repo! The whole java thing's a bit of a mess from a 'casual user' perspective. Some packages won't work without the sun-java6 ones. Some appear to be optimised for it. There's at least one that I know of (but can't remember the name of at the mo - it's an IDE though) that refuses to install without them!

My naïve self would have thought to try and reduce the reliance on java, but of course the cost (of any type) would outweigh any potential benefit.