Structure/feature

It's because it was always this way and it never got changed. However, we have some plans to change them in the future.

@mr mine said

Structures are often saved as features for several reasons like 

Allowing players to build and customize structures in a game empowers them with a sense of agency and creativity. By saving structures as features, players can design and construct their own buildings, fortifications, or even cities within the game world. This feature is prevalent in many sandbox or simulation games, where players have freedom in shaping the game environment.

Saving structures as features can help optimize game performance. Instead of continuously having to generate or render structures in real-time, the game can load pre-defined structures as features, reducing the computational load. This approach is especially useful in open-world games with vast environments, as it allows for a more efficient use of system resources.