Games/mods can add this archive as a dependency and map authors can then use featureplacer in Gundam RTS/Evolution RTS/Other to place features. Mapconv already has support for featureplacer configs.
Adding this archive as a dependency also enables that game/mod to use maps that were previously limited to specific games. For example, many of the EvoRTS maps. (I.E. General Caiaphas' Revenge - Attached screenshot)
This also allows for map sizes to be smaller as there is no longer any need to include the textures with the map.
Additionally, maps may also call this archive as a dependency. Maps can also include the featuredef files if necessary so that reclaim and blocking values can be changed. The featuredefs included are simply fallbacks so that the features will show up, and most reclaim values are really low (like 10 energy, 10 metal, etc).
Basically, the point is that mappers can change the features up however they like with this archive.