I read (in an article of breeder interviews) that Malaysian seramas are sometimes "trained" by placing them in extremely narrow boxes so that they have to hold their heads and tails up, or putting them in small containers with most of the lower edges blacked out so they have to lift their heads to see out. That seems like it might not be good for their spines in the slightest, and it explains why and how some of them have the extreme stance. I don't see why that's considered attractive, it looks like the bird is broken somehow.
And I'd say that blocking the bird's view is not something that "doesn't cause any issues". It interferes with the bird's ability to function as a proper bird.
In my opinion, it's irresponsible and potentially cruel to breed animals or modify them so they can't perform natural behaviors. For chickens, those natural behaviors include (but are not limited to) pecking/scratching at the ground, fluttering, jumping, and being able to see. The Malaysian seramas can't see properly, and I can't find any video of them doing anything natural. They're fed from raised containers, which indicates to me that they can't reach the ground. To me, that's in the same category as amputating a perfectly healthy dog's ears and tail or breeding pugs that can't breathe right. The aesthetics of an animal should not be placed over its ability to function, and it shocks me that so many breed standards value shape over health.
Now, American seramas look better. They're still bird-shaped, like the ones in the top video, and I can find videos of them scratching and acting like birds. They have that nice confident stance, but still function. I don't think people should be encouraged to breed for micros, not with all the heart issues that come with those birds, but I can get more behind American serama shapes. I want some, when I can keep chickens.