Well, I enjoy them, and enjoyment is the point of me playing this game. If you like things like Minecraft or Terraria/Starbound/the building portions of Valheim, then you can find enjoyment in outpost construction. Otherwise, you might like it as a way to make resources or a way to store things and have a living space without resorting to a ship that you're locked to because any other ship not made to accommodate all of your crap and need for workstations won't do.

The pros are not purely creative, but that is a pro if you're into that. Every game has parts that some people will like and others won't like, just because you think sandbox elements have no point by definition doesn't mean someone like me won't enjoy noodling around in Garry's Mod without any mechanical incentive. Exploring the mechanical space of a game and creating just to create can be fun. Not for everyone, but it can be in its own right.