Because your heart meter is hidden while you're falling down, it didn't occur to me that I could lose more than 1 heart while falling--the red indicators didn't fully signal to me what was going on.
Great point -- the number of hearts you lose is tied to the distance that you fall, but those distances are opaque.
The mystery of how much damage you take is in that sense somewhat intentional. We want to punish not planting checkpoints, and not fully knowing how hard that punishment will be is in the ideal case part of the mental calculus that makes deciding whether or not to plant a checkpoint suspenseful/interesting/difficult. The feedback probably isn't quite there yet to make that feel fair yet.