Given that multi-variable calculus is accessible to college freshmen, and millions learn it every year, it's hardly incomprehensible.

You'd be right to be suspicious of the Space Shuttle though.

You may have noticed that it's not going to space anymore. The excessive complexity of that system (and the resulting disasters) is the reason for that.

Simpler (and far less capable) Russian spaceships, meanwhile, kept operating.

Complexity may be unavoidable, but it better yield more value than it takes away. It's a trade-off. There's nothing good about complexity in itself.