Merging all the continents would create a different set of problems. Just off the top of my head, how would you handle characters with the same name? And how would you implement character limits? Right now, you can significantly limit the amount of influence one player can have by preventing them from having more than 1 or 2 chars per island. If all the islands were one, how would you handle that?
I do have plans to improve island geography; however, I don't think people would be very happy in general if I just swooped in and completely rewrote their islands, any more than they were about the Ice Age.