Windwall vs braum and taliyah ults

Not really no. Don't get me wrong, Yasuo is one of those broken champions where he's REALLY strong as an individual champion or he's really shit. Since he's highly marketable (like Lee; their plays look flashy and likely to draw in fans) they're keeping him on the strong side.

With that said, Yasuo has little tools to really effectively counter against projectiles in early game situations. You can say nerf the wind wall but if you do, you're gutting his kit to a point where he cannot survive laning phase. Perhaps in bronze-gold skill level, it's likely it won't make much of a difference (because what I'm talking about is primarily focused on that laning phase/early). However in the ranks of higher ELO's, that Yasuo will come out of laning with no gold. You can try to compensate by buffing other parts of his kit but then you'd run the risk of simply making him uncontrollably strong as well.

It'd be like gutting Lee sin's kit. Sure he falls off but he's easy as hell to play and pulling off that ward jump, ult, Q combo and combo smiting are not hard you just need to practice. These two are both highly marketable. They generate a lot of fans with their flashy plays and looking cool. Skins and the like. Pretty certain Yasuo has gotten more skins than Diana and Diana has boobs with awesome back story. Why? Yasuo makes cooler and flashier plays that makes people freak out in the audience and go "OOOOOH." Ofc I'm making speculative statement here but I doubt they'll remove or nerf that wind wall any time soon.

Removing the size per level and making scale with duration imo.

Yasuo is rewarded with quick reflexes after all. His wall should showcase that more.

Perhaps, but something of similar function would have to be added to Yasuo's kit in the case of such a rework. He needs a legitimate way to combat ranged harass if Riot intends to keep Yasuo's anti-range niche, and the combination of mobility, passive shield, and active W do exactly that. What they shouldn't do is just take away Windwall's ultimate-blocking capability, as that would detract from the ability's current clarity.

To wit, the ability is very binary in its functionality. Projectiles are destroyed, nonprojectiles are not, and one works around the W by either repositioning, waiting it out, baiting it out, or simply avoiding the use of important projectiles until the Windwall has been used. Braum's own Unbreakable has similar enough traits that changing one ability would almost necessitate the change of the other, which would constitute a substantial nerf to a champion that needs no such thing.

If Riot feels Yasuo shouldn't be so casually destroying ultimates, then he needs to have his W reworked into something closer to Fiora's Riposte instead of removing functionality from the ability as it currently stands.