Because readability is really important. We can't do much to improve monspaced environments such as the terminal, but most documentation, even man pages, is rea

Because readability is really important. We can't do much to improve monspaced environments such as the terminal, but most documentation, even man pages, is read in the browser. Using an ASCII ‘-’ to indicate a minus sign in a mathematical expression is quite bad for readability. It is usually less of a problem to use it as a hyphen, but a real hyphen will generally look better.