I am running 10.7 Enterprise, and I notice the same behavior. I wish I could filter based on the cached map service, as my feature is made up of 10's of thousands of points, and it is not ideal to host them as a feature service.
The other work around I could find is adding the map service as the rest service URL, and add layer from web. However, this will draw each feature similar to as a hosted feature service. Depends on your scale and amount of features to whether or not it will work.