Doesn’t work. Take, for example, Crash Lightning and Stormstrike from Enhancement Shaman. Crash Lighting has a 6 second cooldown, Stormstrike has a 9 second cooldown unless a proc puts it on instant cooldown.
So there’s no time where you’d want to cast Stormstrike when Crash Lighting is off cooldown, but there are times where you can cast Stormstrike when Crash Lighting is on cool down.
Castsequence used to deal with this by doing cascading past spells on cooldown until it hit one that wasn’t and fired that one and only that one. Then Blizzard removed that.
That isn’t my point. My point is opening up a test dialog to enter text into box to create a new button to then drag onto the bar is something that a great many players won’t dive into, even if they have sites giving them premade macros. Because it isn’t visual. And there is no reason for it to be. There is nothing they do that cannot be served by drag/drop + checkboxes.
Just as an example I was a programmer back in the naughties, these days I live in SQLLand 8-12 hours a day at work. I scrolled around your post and Noped right out. My wife, who has far less patience for such things, probably wouldn’t have even opened your post. Can I do it? Sure. Do I want to? Nope, I’m playing this game to get away from the 8-12 hours of trying to make computers do what I want them to do, not to recreate my day.