To me, the most interesting part of Metafont is that it can take parameters. So your font could, for example, take a parameter for weight, letting you create as many different weight variants as you like. You can use one algorithm to create a Thin, Light, Regular, Medium, Demi, Bold, Black family of fonts. Or you could put a skew parameter in to generate an Oblique version (though true italics would require a separate algorithm).