back in stormblood, there were abilities that would change into others depending on whether you were on tank stance or dps stance (such as inner beast and fell cleave), so why not do the same for AOE?
everyone is on "single target" stance by default, then pressing the AOE stance changes your skills to their corresponding AOE versions.
1-2 combos turn into the AOE combos, fell cleave turns into decimate, upheaval turns into orogeny, edge of shadow turns into flood of shadow, senei turns into guren, shoha turns into shoha 2, etc.
instead of needing 4-9 different keybinds for your aoe skills, you only need 1 to turn AOE stance on and off.