Where did the wallpapers go?

I am having the exact same issue. Here are the steps I took -- but be forewarned: I was not able to fix the problem.

I first backed up my iPhone to my MacBook Pro, ran Time Machine on the MBP, and then performed a full restore through iTunes. Once fresh firmware had been installed on the phone, I then proceeded to restore my settings from the backup I had made several minutes earlier. The wallpapers were still all blacked out.

I then manually deleted the copy of the iOS firmware in the iTunes folder within my user library, and asked iTunes to perform another full restore - effectively forcing it to obtain a clean copy from Apple's servers. Same song and dance and several minutes later, I see a completely black repository of default wallpapers.

So here's the thing: If, after a full restore, I choose to set up the phone with new settings, the default iOS wallpapers come back in full color. But in doing so, all SMS/iMessage histories, and all app settings/databases are lost. A little bit of research reveals that there is no way* to restore only certain portions of an iPhone backup (unless you JB the phone); with iTunes, it's all-or-nothing. I have one word for that: unacceptable. Long story short: I've decided I can live without the default wallpapers because I really do not want to lose my SMS/iMessage histories.

*Decipher Text Message, MobileSyncBrowser, and iBackupBot all failed me in this regard.