Sorry I hadn't participated in this conversation much, I've been a bit tied up and will be until next week. Because I haven't played around enough with community developed maps, I fail to appreciate this. As I understand it there are two separate issues, one of functionality and the other of aesthetics. Functionally, the map maker needs reliable methods of creating blockades, so we have these nice pinch points like in Overgrown City (one of the few I've looked at). Next, we need a variety of ways to do this to be aesthetically appealing and believable (matching the theme of the map).
One thing we don't have (yet) in Glest or GAE is cliff walls, or blockages caused only because of the incline or decline in the map, this should help -- but also a way to have broken ground, so it's not just a very steep grassy surface, because in nature, the ground breaks and exposes the dirt, rocks and layers when this happens (usually because of water erosion). That's what I think is needed, but that's probably a topic for another day because it will involve bumping the map version and having a new map standard as well as making sure that both map versions are supported. If we're bumping the map version (i.e., adding to the map format) I'm personally in support of better water functionality, so we can have bodies of water at different altitudes and flowing water (water falls) and also have differing water behaviour, like the difference between waves in a lake and waves on an ocean shore (although we can probably manage that via examining water depths).
But back to the original topic, I guess the best thing to do is leave it like it is for now, or make it a setting when the game is started, but in the future, I believe that there should be a better visual distinction between a map object that is harvestable and one that is not. I also think that the minimap should have some way of illustrating what is walk-able and what isn't (also another topic).
