While this would be nice, I'm pretty sure it would require a level of memory access to the game that windower4 doesn't really support. I dunno about ashita though.
Basically, windower4 has no freaking clue when your macro palette is open or not, much less which palette you are looking at. You could work around the former by detecting key strokes(Controller would have a harder time there), and this would still have some jank cause it'd count any ctrl/alt press as opening the macro palette without regard to the current menu... But the latter would, I think, pretty much require direct memory access. It's the same reason we don't have a bunch of full UI replacements already, and just have stuff we layer on top of the current UI instead.
So, you can make a replacement for the macro system, like XIVhotbar does, but there are issues with trying to integrate an addon with the native XI macro system.
Perhaps someone a bit more knowledgeable than me can explain in more detail.