We've been having a lot of issues with the curse client not supporting non zip files. The lack of support for the other various compression formats is a simple matter of not wanting to bloat the client with libs to handle them.
So for WoW and WAR we've decided to start blocking the uploads of the following file types.
This means that if you want to upload a compressed file it should be a .zip file.
We're sorry for any inconveniences this may cause and we may reexamine at this to figure out a better solution in the future. But for now please re-upload file of the disallowed types if you wish for them to be the main file for your project.