As the title suggest, I think CA should consider it. I don't know how much bigger they can make the campaign map but, more a little more ocean between Ulthan and other continents would be amazing. I would love to get a Rome 2 style battle maps with naval landings and sieges. Not to mention the piracy that could be commited on the open seas.
I understand the difficulty of adding this since it would require a lot of resources for mechanics, new assets etc. Perhaps start with some marketing research to see if there is sufficent interest for it?