The hardest part about designing a map is most likely the layout and structure behind it. Defining your routes and making sure it works. Then there is the adding of the "skin" and "textures". When they just reskin a map and give it to us as part of a map pack I feel ripped off. The map packs that are part of the season pass should be entirely new maps. I think if they are going to remake any maps that they should be free to the community as a gift. I don't think they are really hurting for cash at the moment but why not give something for free every now and then. It would go a long way. If not free, sell them for a buck outside of the normal maps and give us our normal 4 NEW maps instead.
PS - Please understand that I'm not saying it isn't a lot of work to do the re-skinning, but just that it isn't as hard as coming up with an entirely new map. It is less than 50% of the work that goes into a new map. Seems like an easy way out later in the games lifecycle.