It’s a design decision. Needs no explanation.
Because it’s more complicated than Superchick, and I can’t be bothered.
I don’t want to endlessly tweak boss attack patterns. It wastes time which can be better spent elsewhere.
No, I can’t special-case the falling speed. Sometimes you get unlucky. Most of the time there’s a window during which you can grab the gift/atom, because it’s not falling exactly at the same speed as the debris.