Something crossed my mind about Intangibility

For frame of reference, I'm talking about those that only make themselves willingly untargetable. Stasis and invisibility are other cans of worms although they share some effects, and those users are excluded. Notice anything common among these avoidance abilities? They're often airborne. That's right, the most debilitating crowd control, and they apply to themselves for a brief moment of power.

Makes me question . . . Why can't other champions just aim a bit higher to hit them? Why don't obviously larger AOEs affect them when they're slightly higher than ground level? Why won't obviously flying characters gain such negation on a whim? Why can victims of popups, be attacked & hit by AOEs, when they're clearly higher in the air?

Obviously there's game design logic I'm taking some out of context, just for the sake of pointing out an inconsistency. However the last one is what I want to focus on. No-one is a fan of being juggled. But what if it was changed so that being hit by an airborne effect, made you Intangible for it's duration? Collision effects would still carried out while the victim is stunned as normal, but at least it would require more coordination to stunlock with airborne effects. As it stands currently, mercury treads are useless against all airborne effects (knock backs, pulls, popups), and this crowd control is becoming increasingly commonplace. Perhaps it's to counteract the mobility & untargetable creep, but that's another debate for another time.