Marvel has long ago moved past only supplying comics for its audience, and now boasts a thriving film and TV section as well. The same can be said about DC.
I think that by changing the tag to just, for instance, marvel we'd clear up a lot of tag issues (non-comic Marvel questions tagged with marvel-comics, marvel-comics questions not also tagged with comics).
Completed, but marvel-comics is still a synonym of marvel and the same for dc-comics and dc to prevent misuse and confusion.