This is because the new official HD texture packs act like a mod, in that they are telling Skyrim to use the textures in the new BSA files in preference over assets in the texture BSAs, AND in preference over assets placed in folders under "data\textures\" in your Skyrim install directory.
One way to get around this requires you to first disable the HighResTexturePack01.esp & HighResTexturePack02.esp from loading in the skyrim launcher or Nexus Mod Manager (or just delete them), then edit your Skyrim.ini file found under "Skyrim\Data\"; just find the "sResourceArchiveList=" entry under [Archive] and edit it to look like this:
sResourceArchiveList=Skyrim - Misc.bsa, Skyrim - Shaders.bsa, Skyrim - Textures.bsa, HighResTexturePack01.bsa, HighResTexturePack02.bsa, Skyrim - Interface.bsa, Skyrim - Animations.bsa, Skyrim - Meshes.bsa, Skyrim - Sounds.bsa
If you dont have a Skyrim.ini in your data directory, copy and rename the skyrim_default.ini into the data directory.
After a little further investigation, Ive found that the choice to implement the official HD texture pack as mods actually works just fine with their new creation kit + steam workshop integration.
Basically, you can upload a mod to the steam workshop via the CK, and in doing so it packs all the assets referenced by a custom .esp file that you create or load into a BSA, and associates it with the .esp.
So, essentially this is not a problem for any mods intended to be used with the steam system, only for old-style texture replacers that worked without an .esp file.
Ive been having a little trouble with the CK's BSA packer; it tends to leave out important files, so there is a need to pack them manually for the time being.
All you need to do to manually prepare a texture-replacer mod for Steam Workshop is this:
First, you need to make an .esp file; the CK can generate one of these for you, it is a database of the values & mesh references in skyrim, however if all you are doing is replacing existing textures, then the .esp file doesnt need to have any data in it, it just needs to be an empty new file.
The next thing you need is to pack the textures into a .bsa file. You want to use BSAopt for this. I got it to work by running the 32 bit exe in administrator mode, with game set to 'skyrim' and settings all unticked. you should be able to figure it out; you just need to preserve the proper file structure for the textures going in, so you would select 'data' with 'use folder' for the input.
The only other important thing is that the .esp and the .bsa file have to have the same name; although, if the .esp file was HAR.esp the .bsa (or several of them) could be HAR - iron.bsa or HAR - leather.bsa; the same way skyrim loads all its assets out of multiple .bsa files referenced from skyrim.esm.
Okay, apparently you can add files to the CK BSA archiver by dragging them from an explorer window into the list; it has the restriction that any files you add must originate from inside your data directory. Seems like a bit of an inelegant way to do things; havent the CK programmers ever heard of adding an 'add file' button? Lets hope they add this feature soon.
That said, I still prefer using BSAopt for now; the reason being is that it allows for compression. I can cut the size of the BSA down by half or sometimes even a third, meaning:
* quicker for me to upload
* quicker for others to download
* steam workshop gives you ~1gb of space to upload mods; if you are a prolific mod author, or creating a very big texture replacer pack, you will need every mb of space you can get.
Edited by QuickFox, 09 February 2012 - 01:35 AM.