A workaround is to use the Nuget Package Explorer and download the package you want into that. You can then edit the folders within the package using Package Explorer to suit your taste and save it into your own Nuget repository. This can be a file system folder or you can get more sophisticated here: Hosting Your Own NuGet Feeds.
Of course this means that you have to keep the packages in your private repository up to date. Clearly if you have a lot of packages to deal with this could become a problem. However it seems quite likely that a future release of Nuget will deal with the issue of local feeds because it’s an issue for companies that ‘restrict which third-party libraries their developers may use’ as mentioned in the Hosting your own NuGet feeds reference above.