I'm all for this being blocked by default, and the same goes for all plugins. But it certainly bothers me when they make it impossible to override their security constraints. Put in an about:config setting to allow Java, and it's fine.
All the heavy-handedness is going to do is force Firefox out of corporate IT environments where many internal websites rely on Java.
They didn't block Java at all, they just stopped it from running the applets automatically. You can still run Java applets without any issues, you just have to allow it by clicking the red lego block.
All the heavy-handedness is going to do is force Firefox out of corporate IT environments where many internal websites rely on Java.