@BobLevine: That kind of generalization is not helping.
For every "skilled coder" there are probably hundreds - if not thousands - of other human beings who don't, won't, and can't get a grip on coding. And they have very legitimate needs for digital publishing tools. You're right: many of them will happily use some kind of template or framework solution. But a fair amount of designers will never touch a tag.
But let's go back to the problem at hand: AEM not playing nice with Muse.
A friendly Adobe staff member discovered that older Muse output (before the responsive hoopla) worked fine, so something must have crept in with a recent Muse and/or AEM update.
Would a straight-forward "dummy" tutorial on how to apply that Gesture API solution help ?
If copying/pasting/editing some necessary code into an HTML file is the solution, then why not let Muse, AEM, or even the Packager handle it ? As a temporary work-around, we consider developing a script and a hot folder to process the code into the files.