I think Minecraft gets it right by using procedural generation to add depth to the existing content rather than making different content.

There's a fixed set of biomes and notable geographical features designed by the devs, so there's no incentive to keep finding unseen ones, but each world gets its own layout and landmarks, so you get to explore the details of that specific generation for days without carrying over your knowledge of the previous one.

In the long term it might get repetitive too, but it does at the same rate as one gets tired of any other game I think.

I agree a lot with your point on Minecraft. The farther you explore and the more you see, the higher the bar feels for what's worth your interest.

When you first start playing the game, a medium sized mountain is exciting. Then the bar raises towards more interesting features (a deep canyon or a village), and then towards really interesting features of land. Finally, you look for obscure biomes (e.g. badlands or ice spikes). By the end, you can go thousands of blocks without seeing something that feels worth exploring.

Luckily Minecraft has other aspects beyond just the exploration.