Dark Eldar, and to some extent Necrons are also a reason not to panic not only for being updated, but the extent they were updated.
After all, Sisters of Battle only have two plastic kits at present, so a full update miniatures wise would have to be extensive. Dark Eldar and Necrons went from slightly shonky forces of limited choice, to a wide range of decent units, and quite a few new ones chucked in!
In short? Chill and relax. The current e-Codex was more than many expected from what I understanding, if not necessarily what the majority wanted.