We are not really limited and can usually adapt a event to the terrain/map, so it doesn't really hinder an admins ability to run them in that aspect. As Postanou mention most of the event ideas you have mentioned already take place with some of them run each wipe, the only ones I have not seen yet are the harbor take over and Rock climbing. What is an issue sometimes is the set up, and take down which can take a bit of time depending on the event that is being run.
If I was looking for a dedicated events map then I would want it tailored for events, meaning custom map with zones that already have event stages set up. For example if you have ever participated in charitable rust that is the kind of map I would be looking for, pre built race tracks, arenas, galleries, sideshow games and the list goes on. This however is not an easy task to set up but with the growth in map makers this might be plausible in the future.
So its not a bad idea and I think admins would love it, however one of the purposes of running events is to draw players to servers and increase player numbers on those servers. Having a dedicated map draws players away and doesnt give them that chance to expirence our other servers.