I still think that before Storybrooke was created it was much more difficult to travel to the land without magic. We actually only know of four ways. The wardrobe, a bean, the silver slippers, and the curse. All the other ways, the hat, the water, the rabbit, the mirrors, the black fairy’s wand, the coconut all would have not worked until after Storybrooke existed and was magical. It is a magical land within the land without magic therefore the regular portals all work now.
This makes some sense of it. I recall an episode in Season 2 where someone says The Dark Curse “broke down the walls or barriers between worlds” or something to that effect. But there was also the Apprentice’s portal and door making ability which we never saw Rumple try to take advantage of, right? And was it ever explained why he didn’t try using the magic tree introduced in Pilot?