I had an issue finding your post, and towards the end of writing my own saw it in the suggested posts, so instead of making a new one, just copying what I had to yours.
I totally agree with wanting this to be added. Here is what I had for my post (sorry for any repeated information/idea, again just pasting my post):
For those who have not played her yet, little bit of info. All of her Active Skills do elemental damage. It is one of the things she can change based on her build. It defaults to Shock damage, but Incendiary and Corrosive can be unlocked (5 points into the “Fist of the Elements” and “Brawl” trees, respectively). Depending on how you play, there are skills that play off whatever your current chosen element is (Fist of the Elements has skills that convert bullet damage to the element, for example).
I chose Amara because I enjoy being an elementalist. Picking the right damage type to destroy the enemy. I have all 3 elements unlocked as well (current build: https://borderlands.com/en-US/characters/amara#t="cb__2768336927___p__476948369-5_69544143-5_2421835975-4_466974429-5_335451024-5_1013120097-1_2136538075-3_870613038-3_3314723340-1_1889856087-5_1746620149-5_3380637792-1_2855324264-5___e__89168977-3421632180_1572227138-2784015595_3806476316-3989481719").
The main issue I have at the moment is the time it takes to switch between the elements (mostly an issue in multiplayer, due to skill tree not pausing).
My idea to do this is: Allow holding the Action Skill button (I play on PS4, so L1 by default) to pull up a menu or something where we can pick from which ever we have unlocked. I know it is possible for the game to recognize pressing vs holding (FL4K has his Action Skill for the press, but then if you hold you command your pet to attack).
This idea of extra options when holding a button could also apply to other things (such as switching weapons. Currently the D-Pad is used for marking things, and switching the quests. I like these, but miss using them to swap to a specific weapon. Can add the Press+Hold for say the weapon swap button for changing what the D-Pad does).
That was it for my post. Hopefully others will agree with us, and something can get added. I havent played Moze or Zane yet, so don’t know how something like this could be QOL improvements for them.