Allow for sysops on Wikimedia Commons when they block users to let users who are productive with uploading but less productive in other fields to continue uploading by not letting the block affect both "File:" And "File talk:" Spaces the same way some blocks don't affect "User talk:[Blocked username]", as Wikimedia Commons is important for literally every other Wikimedia project the ability to upload files is needed to be able to participate in some Wikimedia projects like Wikisource where .djvu files from commonswiki are used.
It looks like such a feature will come out of T2674: Allow users to be blocked from editing a specific article or all articles inside a namespace – if I understand that right, administrators will be able to, for example, block a user from editing every namespace except "File:" and "File talk:", which should fulfil your request. You might want to merge this task into that one.
Note that there is technically a difference between editing a page in "File:" namespace, and uploading a file. It is possible for a user to be allowed to edit "File:" pages, but not to upload files. (However, if you're not allowed to edit pages, you also can't upload files, because uploading a file automatically edits the relevant page as well.)
Let's continue the conversation on T2674: Allow users to be blocked from editing a specific article or all articles inside a namespace — thank you for merging, Andre.
In general T2674 should provide the desired functionality to handle situations where a user is troublesome in some namespaces but not all. We still need to decide if a namespace block of File: also blocks uploading, as matmarex mentions. For other namespaces article creation will not be allowed, so it makes sense to keep a similar behavior.