User blog comment:Zephalian/Wake Island Screenshots! and Incoming 2GB Patch/@comment-3554559-20111205061251/@comment-974025-20111205134150

Most of it is probably the B2K assets, which they apologized for not making optional in the blog announcing the patch. I don't think it's a huge deal, as I would bet most players bought the "limited edition" and/or pre-ordered and already own the expansion pack.