I think that this issue was very interesting twenty years ago. With modern high resolution screens, I have to admit that we no longer bother too much...

In the future, we might only use Opentype fonts and use a font like TeX Gyre Pagella as our default font. I am afraid that we need to keep the old (tfm+pfb) Computer Modern as a legacy font so that people can reliably continue to use their old TeXmacs documents (remind that minor microtypographic changes may completely change lines and pages are broken).