Actually i agree there is barely any need for transport. you can easily terraform your way to the next island and attack the enemy lol rather than making a transport to move them over and have to find a beach to load unload them.
I previously didnt really had it in mind but when i realised i found out that is way easier to just terafform mountains to land and sea to land for more space, better caravan routes etc and even build mountains where you want monsters and enemy to keep out 
Like morfing your own playstyle, doing what you want and by end of the day only real challange would be an other players since ai would rather go around the mountain i just put there and face my full army rather than terafform their way to my weak points 
As for monsters, they just happen to spawn in lands where no influence of a city is apparent and sometimes at areas with fog of war on it. simply if you dont want suprice appearances, then just make all this space into sea, thus no monster suprice attacks from there, problem solved 