Comment by TheAceOfHearts

Brood War's longevity is thanks to the map maker, which has allowed the game to be balanced around maps. The size of your spawn location, the ease with which you can expand, and the paths to different bases drastically impact what kinds of strategies are viable. If there's a high ground location, it becomes much harder to break that position as the attacker. The amount of resources per base (mineral patch count, mineral patch size, 1 gas spawn, 2 gas spawn, mineral only) all impact which strategies are viable.

In fact, during the era of Flash's dominance in ASL, the organizers actually started including maps that were heavily Zerg favored in order to put a stop to his reign.

The game is still alive and well, with a meta that continues to evolve, and every season of ASL[0] (the premier Brood War tournament), they include at least one new crazy experimental map. Last season the crazy map was Roaring Currents [1], one of the more ambitious designs in recent memory which has a large number of island bases. Basically if a strategy becomes a bit too oppressive, the map designers can always step in to make it a bit more balanced.

[0] https://liquipedia.net/starcraft/ASL

[1] https://liquipedia.net/starcraft/Roaring_Currents