For players, they see the error is not on their side, but that of the authors and the players can also see the fix is a simple one, download the mapmedia.pk3. This also helps the players to understand just how the issue appeared and why the author did not notice.
On the other hand, simply not displaying the map is not really a good option as often I can not get in touch with the authors. For example, this author has a .RU email address - for some reason I almost never get a response from a .RU email address. If the maps are not going to go up, I really need to tell the author as to why.
I do try to contact the authors when there is a problem. Sometimes the authors fix the issue, sometimes they don't care too much but most of the time I just don't get a response. I think I don't get a response because the anti-spam filters are just too strict and my message just never makes to the author, not because the author does not care.
So that is why the maps go up, mostly because I hope the author will fix the problem and so players will understand that the problem is not at their end.