Sounds like you are asking about the difference between procedurally generating a level (as Minecraft does) vs building a level by hand. Each method has advantages and disadvantages.

Procedural generation allows you to specify a relatively simple set of rules for the generation in order to produce a large amount of data. And we are talking large here. I saw something somewhere that estimated the size of a Minecraft world as several million times larger than the surface area of Earth. That's pretty large, way larger than you would ever be able to build by hand. If a large open world is your goal, procedural is the way to go. No team in the world could pre-build a world the size of Minecraft without heavy use of procedural tools.

Additionally, procedural can help to amplify replay value, assuming the gameplay is built to support it. With pre-built levels, once a player has run through them and learned all their secrets and surprises, that bit of content is essentially "used up". It holds no more surprises for the player. With properly built procedural gen, you can always present the player with new places they haven't yet seen and new challenges, emergent from a set of simple rules, for them to overcome.

The drawback of procedural gen is that it is superficially easy but essentially somewhat difficult. The concepts and broad ideas are fairly simple, and you can get simple results quickly, but to achieve production results you're going to have to spend quite a bit of time and thought. You can pour a lot of time into getting the generator just right, time that in some cases might be better spent pre-building a world and polishing it to a shine.