I heard awhile back during a discussion concerning Gotland that it is where the team placed the city/province that is hardcoded as the Vanilla "Rome". They did this because the island is unlikely to be conquered very easily, thus preventing the AI from prematurely upsetting the script to end the game. I can't remember all of the details from that discussion, but that's what I do remember. AFAIK, eliminating Gotland might cause an AI or player controlled faction to accidentally end the game early by conquering the new city that is linked by hardcode to the Vanilla "Rome". I dunno.

Chairman