Just thought of this right now. It would make the RS world a lot bigger and vaster. I know jagex just made some new monsters but some new areas would be cool. Well post to agree, flame or whatever.

well they are making new lands, they have make the waterbirth island some time ago, they make the braindeath island, expand the waterbirth island, make the fight pits, the fight caves, they are extending the world as i write, but some times they change things, other times they do new ones, those things take time, just give them time to do it, and they are working on a great update right now, the player owned houses and the carpentry skill, so give them time, and you will eventually get more lands and monsters