Well Patch 5.4.2 PTR came out a few days ago, it initially had a version of Karazahn that had no webs or skeletons inside of it, but due to a hotfix yesterday and a brand new patch, the webs and skeletons were put back in. My guess is that blizzard accidentally released something they were working on and were rather quick to do something about it.
So now if you download the PTR, the WMO it comes with has webs and skeletons back in(patch 17614), the previous one is patch 17595 (thanks to Dracbane for informing me of it since you can't get it through the installer anymore).
• As noted by wowhead, The areas by Attumen the Huntsman, Moroes and Maiden of Virtue (Banquet Hall, Grand Ballroom, Gatehouse, Livery, Scullery, Guest Chambers) are free from cobwebs and the humorous decorative skeletons have been removed. The rest of Karazhan is still unchanged.
••• So some areas still have webs and such novelties.
Download Link: http://anthonys-toolbox.org/Webless_Karazahn_17595.rar
This is just the WMO, I don't think there were any new textures added. I think this would be a great addition to an RP Server...I have no idea how this would fair for normal usage though as it may not work properly with the original's vmap and mmaps.