New Seam wizard creates org.eclipse.jdt.core.prefs file with Java 6 enabled

I got a Bad version in class file error today when deploying a freshly created seam and noticed that the War project (not the test project) had Java 6 enabled for the compiler (see screenshot)

1) Why are we actually generating this file ?

2) Why is it Java 6 that is chosen ? (on second run it was actually Java 5 so it is non-deterministic)

3) If it is needed, why only on the war project and not the test projet ? (note: i ahven't tested Ear)

I've seen a couple of questions on Bad Version in Class in the forum so I guess this is not new behavior.