Whilst crytic have said that from time to time they may need to wipe the published missions for technical reasons, and that authors would need to republish them, should this be a regular thing. (Note for anybody that does not know, this does not mean the mission is deleted, you just need to press the republish button)
My thinking behind this is that there are many missions that are just test missions, or grind missions or stuff that people have put up simply to clog up the system. Those missions do not need to be there all the time and many people will just forget to take them down or just cant be bothered to take them down. Basically they could stay there for months/years doing nothing but filling up the lists.
A periodic wipe would clean the system out every month or two and would probably only have the main authors republish who care about their missions would republish.
The downside is that people would have to manually republish them every month or two which would be annoying all of the time, and I guess some people might make an awesome mission then leave the game for a while or for ever and their mission would be taken off and never get republished.
Another option would be to unpublished any mission with an average rating of less than 3 stars. (Un-rated or less than 5 player rated missions missions would not be wiped as they have not had a chance to get past the review stage.)
What do people think, or does anybody have a better idea.