I was thinking... could we standardize straight mutes for trumpets and trombones instead of keeping Harmon as the standard one? I got some reasons why, even if you don't find them enough, I'll mention them:
Straight mutes usually are more used in orchestras than Harmon mutes. Straight mutes have been used in many 20th century orchestral works and other band works (not sure about the latter one but I think so) and could also be used in Jazz or any other kind of music too. Harmon mutes are only (if not only then mostly) in Jazz bands.
I'm not sure about this one: I get the feeling that people will continue developing Harmon mute soundfonts if we standardize something else. While, if we keep Harmon as the standard, I don't think people could develop any other types of mutes... Basically the opposite is less likely (in my opinion). Right now there are already countless Harmon mute soundfonts for both trumpets and trombones, while I, personally, couldn't find more than 3 straight mute sounds, 2 of which were sfz's and didn't work for the whole range of the trumpet, plus there weren't any trombone ones. Those are my results, perhaps others have found decent ones, not sure.
Well, it's weird that I don't see many straight mute soundfonts... they should be more common right? Or am I wrong? What do you think?
(Could be cool if we had straight mutes for all brass instruments... but MIDI doesn't allow that :'( EEK)