[texhax] D. Knuth and Metapost

[Karl Berry]

    If it's true, why doesn't he use directly his Metafont?

Of course I do not presume to speak for Knuth, but mp has some features
that are convenient for diagrams, as you mention.  That's probably the
main reason.

Metafont was, as you know, intended for making fonts.  Having your
diagram be a character in a font can be pretty inconvenient.  I bet
there could be trouble with size limitations, too.

    But certainly he could create himself such facilities with Metafont if he
    wanted to!

He could, but he wants to work on the Art of Computer Programming :).

    Could it be possible to create such macros and facilities

Perhaps. Give it a try!

k