Here's a list of some fair and justified Yasuo nerfs

Well, yeah...

He has a skill that blocks a great majority of hard CC, some of which don't even make sense as projectiles (Like Lulu's Whimsy, Hecarim's Onslaught, etc. Hell he blocks the Mikael active for shits and giggles.). Hard CC that isn't blocked is few and far between, and they almost always require you to launch yourself into melee range and/or pray that Yasuo stands still long enough for the delay to pass.

{quoted}

Braum shield is instant cast.

Braum redirects damage and cc, yasuo just negates it. Braum also isn't a melee adc, and doesn't have an easy way to get to you, so you aren't under pressure to kill him or die in a short window of time. Oh and it also costs mana, meaning he isn't trading just cds for mana and cds, but trading mana and cds for mana and cds.

Janna E is instant.

Janna's shield can be broken, windwall cannot, janna's shield also costs mana and a big chunk of it, and once again, janna doesn't put you in a "kill me fast or die" scenario.

Many defensive abilities are instant cast, the difference is, you have to aim those.

No, it's mostly the counterplay to them and the options to deal with them. Janna's shield is meant to be broken, she doesn't deal much damage and negates it instead, braum redirects things, which in many cases just means nothing(if it's a single target skillshot), aside from that it's damage mitigation on a tank(tanks tank, more news at 11), yasuo forces you to fight or die then negates your options to fight back. Remember when talon and kassadin had silence? Remember why they don't have it anymore?

Yas wall just blocks any which way at the moment of cast, making it not start at his center would fix that.

This is such utter crap I can't believe people keep saying this shit. No, all it will do is give him some more room to outplay himself, you would still be completely reliant on him messing up, that's shit design, he needs more tools to be dealt with even when he isn't incompetent, that has always been the number 1 complaint about him(phrased in different ways), and this has absolutely nothing to do with it.

{quoted}

Any weakness that should exist in Yasuo's kit, but doesn't, is a problem that needs to be fixed.

Here's the thing: the weakness of "yasuo is weak if he messes up" is already there, and it's probably his biggest "weakness"(unfortunately, not a real weakness), so meh.

I do agree Yasuo is terrible to play against and offers virtually no interaction save for a few matchups, but I think you might be a bit overzealous here.

I think you've just played too much against bad yasuos who can't do consistently what they are supposed to, since I play in a higher level people here know better how to use their champion and not mess up things which they are not supposed to mess up(like throwing windwall in the wrong direction, or failing to block skillshots with more than a 0.4 seconds travel time), and I can assure you that yasuo is one of the hardest counters to probably the biggest subset of champions out of all hard counters out there.

{quoted}

Because there are many more situations were maybe yasuo misses by 90 degrees.

90 degrees is still a huge miss, this is incredibly rare.

He still should be punished for that.

Again, sure, whatever, won't solve or improve anything though.

You should always face some sort of consequence for missing your ability.

It's not even missing it, it's not the sort of thing which even can be missed, it's basically misclicking it, which is very different, missing implies that it's something the opponent can work around, yasuo's windwall is instant and huge, maybe you can try and work around it after it's already cast, but it's really not something you can make him miss.

There are MANY times that yasuo should be punished but isnt.

Like what? This one definitely isn't it, throwing windwall in the wrong direction is a show of complete incompetence and as such is extremely rare.