They managed to make morimar fairly open and less 'rat in a tunnel' feeling compared to other areas.
If they want to restrict access based on colonization they could have cliffs/crevasses crossable by structures like rope bridges (like the ones in lufaise meadows).
If you think about it, theres very little to no layered map design anywhere, considering what they did back in zilart zones like sea serpent grotto or den of rancor (yes very nasty places that some hated, but a return to that kind of world design would allow more creative things)

One of the big problems with their SoA map designs is that a number of them are very unfriendly to roaming xp parties with the upcoming job points system.
People will be somewhat annoyed they will bump into colonization reives and certain areas dont easily flow and loop back around to support xp chaining.