Why are there 50mm lenses for APS-C?

BrightEyesOnFire wrote:

What are you supposed to do with a lens specifically designed to offer a 75mm equivalent focal length? Shoot a portrait down to the thighs? Do they not realize that there's a reason nobody makes 75mm FF lenses? Do they think "50mm" is some absolute, unimpeachable measurement whose meaning can never change? Would it be so much more difficult to make a 56mm or 60mm lens?