Desync causing them to walk through doors and hit you from outside buildings while you are inside, for starters.

That sounds like a desync problem

Have you watched their animations while the chase you, they look like they are ice skating after you.

That sounds like an animation problem

Sometimes they hit you 3 times instantly when you get within 5 meters of them.

mmmm delicious desync

They make no noise when aggro is gained, only slight (good) noises when idle.

Sound problem

They don't always follow the "stealth" mechanic, either.

I have yet to aggro a zombie without having stood up or gotten too close. But tahts just me...

But they are "the best" since launch (sadly)... they are broken though, still, as well.

It could be argued that the zombies are the sum of their parts and that each of these features make up what a "zombie" is. However, I'd argue that when the desync is finally addressed and worked out the zombies will suddenly start to function as intended. I'm not so sure that the things you've listed here are problems with the zombies as much as they are problems with core aspects of the game.

For instance, with sound...yes, you're right. Their sound is bugged. But so are gun shots. This leads me to think its a problem with the sound, not the zombie...and that when that problem is resolved, zombies will suddenly "work" without any zombie specific changes.

Everything about this game is work in progress. Even brand new features are still work in progress. It will be work in progress for at least another year or two. In the mean time we all just have to deal with it. Things will break, and then they will break again. Expecting anything other than a work in progress is going to lead to disappointment. The only time you will ever see a complete feature in this game is the day that it launches. Until that day, expect every single little thing to break or be changed.