The drawback is that the generated font won't be the size it claims to be. I.e. the result for the font "20-xyz" could have the height of 25.
That's a *major* drawback for me. The current font names were introduced on purpose to make it obvious which size the font will be, so that you know your choices exactly when you need or want to switch to a different font for a theme/WPS (maybe you don't like the appearance or need one which has a different set of characters). It was inconsistent before, now it is correct even if some characters are broken as it turned out - and with the proposed change it would be wrong again.
I would prefer to fix the font(s), maybe making the same compromises as in the suggestion, if necessary rename. To do this, I could imagine a font fixing and/or analysing script (or so) that would do what you are proposing - but only once and not everytime the font is built and perhaps it could also give the font the correct name. Regards, Marianne
