With the raid ID extension feature some guilds, like <Undergeared>, make use of it to progress bosses without having to re-clear the whole instance. It is annoying for a 3 hour/week blue geared raid to have to clear ICC10 again.
What I'd like to know is if the 3.3.5 brought a raid ID wipe to US servers, or if you were able to keep the extendable raid IDs you had before the patch hit.