I have no idea. It does seem to be an issue that gets some people rather worked up.
For those who are unaware, here is the major problem with mods on a console:
1. With just a few lines of code, I could (maliciously or not):
a. Crash your game.
b. Cause numerous writes to your hard-drive, lessening its life.
c. Use up all the VRAM on your console, causing it to slow to a crawl.
d. Corrupt files.
2. Console manufacturers would, in the interest of PR, have to authorize every single mod that was released (if done officially).
3. There is little ability for modders to work on a console - that is to say, debugging solely on a console system would be torture for modders.