If, as you state, it's the same teams winning most worlds, how would a bigger world change that? The first few 100 players join and the world is decided! A lot of empty space and a longer time to reach the centre but no gain for players or EA as far as I can see.
I support the request for 'different' worlds with 'different' features aka options. However, we've had many threads with suggestions for these different worlds and not many have been implemented as changes.
Maybe a large Firestorm world with Malus and Forgotten attacks, a higher start (and cap) for the player and forgotten bases (as is being 'tested' on the PTE) and a much higher fortress with a lot of water, much more than any worlds so far, would be different enough!