The problem the character has is the Azir or Kalista problem. Both are hard as all getout to understand and use to a baseline and general use, but once they're in the right hands, they become absolute monsters that stomp up and down the competition. When was the last time you saw a god-tier first time azir game? Never. Because these characters NEED to be weak to newer players and require dedication because of the insane power latently stored within them. You're complaining that she can't be both, but she can be. Look at our friend Ryze, and his third rework, or once again, Azir. A character can be EXTREMELY complex and be overpowered, because that complexity gives rise to how strong the champion can be within the right hands.
For example, lets go over release post-bug-patching Azir. If you check the competitive scene for that year, that ungodly year, you will see Azir picked left and right all over the board. He was dominant in the hands of pro players, but the common player had maybe a 45% winrate, if not even WORSE. But he was blatantly overpowered right? so much so Riot had to nerf him continuously inbetween minor buffs just to make him reasonable for both pro play, and soloqueue play. Akali is a strange monstrosity in that she's a soloqueue monster that requires high skill, but pays off hard. she's a champion that can burst so quickly it puts ZED in a run for his money, and that's saying something. Her early will either dominate or be dominated depending on the skill of the player, and that checks out, because if put in good hands, she's almost guaranteed a strong snowball or picks whenever she can make them. I'm an absolute novice with her and I can see the potential she has and its staggering, what just a simple rotation of abilities can do. NEVER, and NEVER say "You can't have it both ways" in league unless Riot states otherwise, because it can and will happen. To prove my point further, lets scale her kit to an average assassin.
Zed and Talon both have 2 dashes, in Zed's Ult and Shadow (technically blinks, but lets just call them mobility), and Talon's vaulting and Q. Zed requires nothing but either clicking a within range target to reach them with his ult, and his shadow(s) is solidly rooted in place. they can potentially deal bonus damage and be teleported to, but do have required ranges and time limits outside of his ultimate. Talon requires Terrain, and a target. Not bad, one is solid movement and the other is point and click guaranteed burst, but can ONLY move towards a target. Akali has 4 separate dashes in her kit, her E not only provides a backdash of mobility (it can have her go over walls, and disengage if necessary) while dealing damage, and if it hits an enemy (minion AND champion), she can dash to them at ANY range, as a basic ability. Little known fact, this also works on her shroud, where she can use the shuriken to mark a spot in the cluster and dash to that too, which gives her 3 potential targets for 2 dashes, a disengage, and followup. Note the followup ALSO deals bonus damage AND can trigger her passive so you can hit a 3 chain burst to trigger your Passive auto, the shuriken, the damage dash followup, and likely either a shock, or dark harvest. Note these scale all VERY well and deal both physical and magic damage. Zed and Talon only have Physical damage, and other assassins normally deal either specifically magic or specifically physical. Akali gets BOTH, and SCALES with both, making her incredibly adaptable too. But Akali ALSO has 2 other dashes, centered in her ultimate. She can dash forward which deals a .5 second stun (its still a stun. Out of all assassins, Stuns are incredibly rare, where roots are a bit more common, this straight up disables or halts a channel ability) and deals a slight burst of damage. Her followup then deals a significant amount of damage + a basis of how much the opponent champion is missing. The ONLY other assassins to have % of missing HP damage dealt as extra is EKKO, and Evelynn. Literally only those two, and both ONLY scale with magic damage. This scales with both physical and adaptive, and can hit MULTIPLE targets. Eve's ult can hit multiple targets but also moves her away, where as Akali can both move out, and INTO other low health targets...
Do you see what i'm getting at here? Akali simply lacks a very solid limit to her potential, which isn't a bad thing. A difficult character provides interest and dynamic gameplay, but in the difficult, an insane award can be found, and Riot and a lot of pros know how devastating her kit is, and the sheer potential output Akali can provide to carry a team whilst not only being untargetable, but constantly moving around the map and making swift work. I wouldn't say she's flat out broken, but overpowered is decently reasonable, as she's simply too strong and safe at some points to be punishable, and this is all while she can easily build whatever items necessary in order to deal with a target. And now with new items, such as death's dance, and her naturally best item, hextech gunblade, she's healing from 2 SEPERATE ITEMS, + she's one of the few assassins with energy and a built in heal for a damage ability that lets her have distanced trading. She has one of, if not the, most potential of any character right now, and like the poster had said before, she's difficult while being overpowered because once someone has put so much time into learning her, it stops becoming "wow this guy is good" to "How am I going to overcome an obstacle when it has all the ways to disable me from challenging it?". Skill difference should be shown, but if the skill difference also enables an insane character, it stops becoming fun for the challenger, and forces them to learn an equally stupidly strong thing to counteract it, if that option is even available. Some people don't have every character to a T, so you can't blame a player for not having the specific skills to shutdown an already impressive player on a straight up terrifyingly strong champion if the counter is not within their champion pool, or maybe the counter was removed altogether. Bans work, but everything has a chance to slip by.
Sorry for the long post, but I think you're being very narrowminded in saying a character can be complex but it is impossible to have multiple descriptions. Because it is. Being complex and underpowered is an exact description of Azir or Ryze right now, or simple and incredibly strong like Darius. Don't narrow down an opportunity to see from another players perspective, especially the common player. [slayer-pantheon-thumbs]