Well for some of those at least, it's not exactly clear what copyright to put them under. The comic book heroes really fall prey to this. As an example, just recently I had a Captain America picture, and I didn't know what the default series that he fell under, so I just added the Marvel tag.
However, if we can clear up those dis-ambiguities, I would have no problem to restricting the use of company tags to the fore-mentioned occurrence of company connection or logos.
1. Decide what the default copyright is for each of those disambiguous characters
For the Captain America example, I'm not sure Avengers or one of the movies is right unless the pictures specifically alludes to one of those. Therefore, we may need a Marvel universe or Marvel (series) tag to cover these kinds of images. Same for DC, i.e. DC universe or DC (series).
This sorting needs to be done I believe for many of the characters under the above-mentioned company names.
2. Adjust each character's wiki so that the default copyright is known/mentioned
Currently, the Captain America wiki has the Marvel tag in it, which shows up when you do a related tags search, which is why I added it. If #1 gets sorted, then those bad tag entries should probably be removed and the correct entries should be added. Though, just the tags themselves need to be removed. The text can remain there. It can even be highlighted if needed by making the text bold like this.
3. Add these default copyright tags and their usage to the associated company tags
So in a sense, each of the company's wiki pages would function like one of the list_of_* wiki pages.