Hi, as an Akali Main let me give you my opinion.
First of all start by reading the patches she had to endure over the past season. Where she came from and what remains of her right now.
Patch History:
http://leagueoflegends.wikia.com/wiki/Akali/History
Akali currently has a nearly unmatched trading pattern after level 3 and if you do trade with her then she for some weird reason has built in sustain that no other champ has in the game to this degree. Not even Nasus with his life steal heals as much as she does and let's not forget that once she hits 6 whether you were ahead or not your laning phase versus Akali is over(Gunblade and just FF).
Akali excels in sustained trading. This is simply what you do NOT do when you play vs her. Taking away her sustained trading would be the same as taking away Draven his Axes. You would end up with taking away the identity of given champion.
Another issue is that she can build 
and not only does she heal for ludicrous amounts but she can still one shot any squishy effortlessly while being tanky.
Any champion in the game is free to build the same item path (except the few items such as Victor's). Ninja Tabi in this case is completely situational imo. Gunblade is core to her build. I would even love it if they make it Akali Only just like Victor has his own item. But hey, that's another topic.
Zhonya's = normal item for any champion that wants to survive huge damage, cc, etc
Void Staff, again, completely situational. If the enemy goes Magic Resistance you go Void Staff on Akali, if the enemy builds Health or Armor you go Lich Bane or Liandry's.
Deadman's Plate = I guess it's an option, even though I think there are better options in general this could have been very strong on the Akali you played with/against. Depending on her playstyle, enemy item builds, etc
Spirit Visage = This is indeed a massive buff to her sustained healing, even when i don't take into account runes, supports that heal etc. But once more this means she gave up a possible offensive item just so she could sustain more.
Question yourself; if the sustain was that big of an issue, did you build anything to stop it? For AP there is Morellonomicon. For AD there is Executioners Calling. Either give a certain amount of Grievious Wounds.
I think her shrouds time needs to scale because 8 seconds of literally being unable to target her or see her is just outright unhealthy and poor design. Atleast before you could use pinkwards but now unless it's AOE there's nothing you can do while she's shrouded. Please make her Shroud time scale with ranks instead that way it's weaker early and scales into the late game.
I can agree on Shroud time scaling through the levels, in fact I think it would be healthier since most champions their abilitys scale with their level. I do however not agree on the statement regarding the Pink Wards. For the past few seasons it was a given to lane with a pink ward when you faced akali. If you were ranged such as Orianna, Syndra, etc You could just place the pink in the middle of the lane and ignore her Shroud for the entire laning phase. That was completly bs. 75g to disable 1 champion his abilitys. And it's not like Shroud still gives the scaling MR or Armor it used to give. When akali trys to make the 4 basic hits on the ward you simply had free poke or a free kill.
ACTIVE: After a 0.25 second delay, Akali blinks to a nearby location, leaving a smoke cover for 4/5/6/7/8 seconds at the location before cast and incurring a global cooldown of 0.5 seconds to all her other abilities.
Most people don't see that this change is both a buff and a nerf. Yes she can blink over walls now, however she can not place the shroud where she wants. The shroud is now around her (Point blanc). Resulting that she can not shroud over a wall to grant vision or jump on a target with R - Shadow Dance. She no longer can place it away from herself to slow enemys and save a teammate. Now she has to risk her own safety in order to do so. (Which is healthy imo)
Also, like many others, she snowballs, she will outlevel and if 2 levels above you she can simply dive a squishy that is full HP under a turret. But many champs do that. Some without even having to take any damage at all. Think about Fizz, Zed, LeBlanc,..
When a champion is far ahead it will eventually 1v5 an entire team. But that goes for pretty much every champion.
Also; winrate and pickrate often go hand in hand.
