And yet some people complain about all the "useless" biomes like plains, tundra, oceans, etc. - Mojang's job is impossible. You want variety and diversity and exploring, other people want everything easily accessible within 64 chunks of the spawn.
People complain about them being useless, because Mojang added them in a whim as a half-assed implementation, with NO ACTUAL FEATURES. IF, and IF they had their specific resources to be gathered from them, speecific generated structures, fauna & flora, they wouldn't be so useless now, would they?
That's the problem. Oceans have had nothing in them but squids since INDEV. Snow biomes haven't given us anything but SNOW since they were added. MOST biomes are like this. Minecraft as it is right now, in Vanilla, is a very bland and boring landscape, extending for up to 2 million blocks in every direction. You dig down, plant trees, build a massive house, play around with redstone, get bored, download mods, and then suddenly your world is populated with actual features.
This is the actual state of minecraft. There simply aren't enough features in vanilla, to make you really want to explore the world, or even leave the spawn area. Every different biome just has different Aesthetics, and no actual features or unique resources. In fact, ExtraBiomesXL also suffers from this syndrome.
On top of that, there's the thing about updating the engine, making it more optimized.