Asteroids are good for lots of things

Tired of the same old space rock tumbling around in your home star system?

"Aw hell, who forgot to wind the wheel this morning?!"

Asteroid base - Captured asteroid serves as a space-based port; they can be dug into to provide cover, even disguised to appear as a regular 'ol space rock.

Mazes - Asteroids make for great zero-G labyrinths of any scale, including startfighter-sized tunnels if not the traditional humanoid-sized dungeon crawl.

Really big projectiles - Starship Troopers taught us they could be used as ammo for massive rail-gun type weapons with catastrophic consequences.

The trip to Grandma's just became one boring car ride.

Raw materials - That giant habitable ring around the sun needs ore! Where do you think it's going to come from? The value of an asteroid's mineral content has been valued in the trillions (today's dollars). Asteroids = treasure!

Colonization - Panspermia is the theory that life was seeded from space, via comets and/or asteroids. What happens when life already exists on a world that's about to be to get hit?

"Can I hang with you guys? Do you want to ride on my event horizon? Hey, where ya going? You know you can't escape, right?"

Food - Need to feed that rock-munching space kaiju? How about that stellar fragment that keeps following you around--or that sentient black hole that won't shut up?

Interdimensional jump gate - Buckaroo Banzai traveled through solid objects to breach the 8th dimension. What if phasing through rocks (or some sort of mineral found in them) were the only way (or easiest/quickest way) to travel between dimensions.

They remember what you did with the garden hose.

Insectoid alien nest - Weaving together several asteroids to make a hive or digging into the rocks to hollow them out for an alien ant nest.

Giant space geodes - Ultra rare jackpots for space miners or as a container for micro "Hollow Earth" adventures.

Monster - Space rocks need love too. And when they don't get it, they get angry, maybe even a little hostile. Think how many rocks there are between Mars and Jupiter that might have it out for us...WE'RE SURROUNDED!

Suggest more in the comments below, please!