Kayn's Ultimate

I have been looking at Kayn's ultimate for a while and there's something I don't really understand ... why in hell this ultimate doesn't get cooldown reduction when its target dies prematurely? Seriously, imagine yourself as Rhaast ulting an enemy tank to heal up for the sake of survival and your teammate just kills him ... not only you get out with absolutely nothing, you also lost its cooldown.

I understand the untargetability plays a crucial part in this matter, but compared to the real effect of the ultimate - Which most of the times is the damage and/or the healing - I think in these cases it's too much. Maybe reducing its cooldown if the target dies in the second second or even applying the heal (in rhaast's case) regardless, should help. It's just my opinion anyway.