Currently mathtex does not have support for anything other than TrueType fonts. However, matplotlib can make use of the 14 'core' fonts that are part of the PS/PDF specs. The metrics for these fonts come from AFM files.
The question is how important are these as a feature? While I can add support for them into mathtex I am unsure exactly how useful they are. Mathtex will always be built with FT2Font (FreeType) so it does not have any advantages dependency-wise.
Hence, I am interested if there is a demand/need for them.