At 15.05 +0200 2001-05-14, I wrote:
>Don't overestimate Knuth's foresight here. He needed some place to store
>the font-related information TeX would need, so he simply packed all kinds
>of information into a single file.

I now see that I was wrong about Knuth's role in this. tex.web says:

  The format of TFM files was designed by Lyle Ramshaw in 1980.
  The intent is to convey a lot of different kinds of information
  in a compact but useful form.

Lars Hellström