Hrmm, I wonder if maybe it is something with a multiplayer server? I morphed into a bat and found the perimeter of the land, then went North, South, East, and West for about 30 minutes each. Nothing but ocean biome. But with the number of dimensions, like I said I can still enjoy myself. I remember with some of the previous mods and versions of MC there were ridiculously large ocean biomes, but still land eventually. I would be okay with that, too. Have you been out the roughly 4k blocks from spawn?