It's just a different animation....
What you wrote works also on the other way: just because you see sluggishness doesn't mean they are here.
It's just a different animation. Clearly you can like it or not, is subjective.
But blaming Apple for something that many others like......
Even I saw the sluggishness of that animation when tapping the omnibar. That's what made browsing experience terrible on iPad Air 1.
I fully blame Apple for that as they clearly know about it during testing. It's so damn obvious. Which makes me believe it's been done on purpose to render older tablets obsolete compared to their newer shinest Air 2.
This info is not even subjective. The slugishness of that animation is by design.