I never really thought about this. Since it introduces a movement-related change, it would need to be implemented such that it doesn't mess with the player's existing movement code. (That shouldn't be too hard, especially if it's tied only to a specific object, but still, the consideration has to be made). Additionally there's the question of exactly how it functions - does it not affect the player when the umbrella is not deployed? Therefore being an exact opposite of the current object, or does it additionally cause her to fall faster without regard to the umbrella, etc? The latter is when it has to be implemented very carefully and while a downdraft is a neat idea, I personally fear for entire screens consisting entirely of updrafts running into downdrafts and navigating between them in a perilous way. As Ego stated, it's actually quite easy for to Juni to fall in comparison with gaining height (even by climbing she's much slower), so the idea of using the object for any sort of navigation besides in conjunction with the updraft object in a confined and challenging series of screens is sort of besides the point. The problem that mainly worries me about using these in a challenge, particularly in conjunction with the updraft is that it's going to be hard to tell them apart. And again, navigation-wise, they don't offer a lot Juni can't do by falling already.