Hello Sinelius, as well as everyone who has commented!
Thanks for the suggestion that you have brought up to us! Unfortunately it has been declined at this time. A large part of the server is the playerbase and the community, and very often players from different worlds communicate to talk or help each other, whether that be through global, trade, roleplay, quests chat etc. If a player needed help on one world and there was no one to help them on that world, they may not receive the help that they need that they could get from a player from another world. Additionally, having separate chats per world would make moderating chats a lot harder, as there would be 2-6 chats to moderate depending on how many worlds there are, as opposed to one. Once again, thank you for the suggestion - we really appreciate seeing your thoughts and ideas!