I wouldn't say so. With the increased mountain height I'd argue the terrain is more realistic than ever, and not boring.
> In the b1.8 update [September 2011], the terrain generator was subject to a rewrite aimed to make the code simpler, and make the terrain more realistic. ... at the time it caused quite a controversy, a thread on the Minecraft Forums decried the new terrain as "boring".
What does "realistic" mean to you? Are you looking at it like a geologist? If we follow rland's idea to completion, Minecraft players should look for kimberlite pipes to find diamonds, etc.
I'm certain some people would love virtual prospecting like this. But I strongly doubt the game would be as popular.
I'd say if you compare the first two set of screenshots. It is more realistic since you don't get as crazy land formations. But falls short of creating significant mountain ranges to compensate, making it less realistic in a way.
The first image, 2011, makes me think of tower carst formations, like Ao Phang Nga National Park or the Li River. It's indeed a "crazy land formation" in that most of the planet is not like that. But well within what a more physics based model might generate.
The second image, 2021, makes me wonder what's going on. How did that concavity appear in the bottom left? Was it limestone? Sandstone, like NM's Natural Amphitheater or CO's Cliff Palace? How is the top of the concavity supported, given that it appears to carry a lot of earth?
What is the geological connection to the ridge above it? How is the ridge supported? It appears highly eroded. Where did the scree go? (Shouldn't some have filled in the exposed concavity?) Why is the transition from light-colored to green so clearly delineated?
In the real-world, large cave systems are rare, and walkable ones even less common. But they are also part of what make Minecraft fun.
So yes, I think a more realistic (in the physics sense) would be less fun than what Minecraft does. (Excepting, perhaps, a small number of more geophysically inclined players.)