It is probably hard to appreciate what a feat of engineering this is now but back then I'm sure it seemed incredible. And imagine all that this made possible. Surely the challenges of getting a train over this set of mountains were present when trying to get trains over other mountains.
The train was an incredible piece of machinery that fundamentally changed the way people traveled. The horseshoe curve basically made it possible for trains to travel anywhere in America. Think of what a revolution this is. This single invention enabled so much western expansion. I can see why they have gone to such lengths to honor it.