I personally think the more the better, how can there be too many maps ?
But, maybe the maps need to be organized and categorized better. There are maps that are extremely specialized and nothing like "Risk". I know there is an advanced game play attribute, but some maps are beyond Advanced and take it to a new level, then they aren't everyone's "cup of tea". Then some Maps just are not fun with certain spoils or game play settings. Sometimes you play a map and it just sucks with Flat rate, but the same map might have great flow on escalating.