Okay, I'll just jump here because you have terminology totally wrong.
Camoflauge is very healthy, stealth definitely is not.
Camoflauge IS stealth. Stealth is any mechanic of trying to not be seen by enemy where they normally have vision. Stealth then either can be Camoflauge or Invisibility, which is what you are talking about.
Making true vision not be able to see stealth was a horrendous change
True sight still reveals stealthed champs, both camoflauged and invisible. Turrets, for example, provide True sight. Invisible champs cannot turretdive you without beign seen.
Akali's isn't great, but at least it's more balance-able since she's confined to an area to have that stealth (although it makes it a better defensive tool for her when her stealth should be offensive... I think it would be better if her shroud increased the rate at which her cooldowns were refunded but lasted less time (so she could get her abilities back in the same proportion from her shroud, but less time passes for allies to come rescue her).
I don't understand how is it supposed to be offensive? It basically works the way you describe. Her cooldowns are around 2 seconds, maximum 6-4 seconds and less. How in the seven hells do you want that to refresh faster? She legit has one of the most frequent combos. You are supposed to use the shroud to deny the enemy their combo while always waiting the second or two for yours, up to twice in one fight. Just recently I laned against Kayle - the shround worked perfectly to deny her advantage of her ult until it went down and I combo'd her one more time.
or even see their outline with a red trinket.
You still can see both invisible and camoflagued champs via red trinket as shillouette.
Stealth WAS an interesting mechanic when you could see the champion with a pink ward ... It made for good decisions
No it either rendered supports to be pinkwarbots, made you waste money for counter to something that was still unstopable or literally easily destroyed core dependency of champ via relatively cheap item.
Seriously half of your statements are just wrong from you having no idea how stealth works and there are 12 people who upvoted it out of their own ignorance. Gameplay boards in a nutshell.