Should Zilean's ult heal more similarly to Ekko's?

Disclaimer: I am not at all saying that either Zilean or Ekko are OP or UP, in fact I hardly play anymore due to school and whatnot, I am merely curious.

What would be the implications of Zilean's ult reviving the target with a base amount of hp plus an amount based on the amount of damage they took in the past X seconds? Would it be necessary? Overpowered? I'm thinking that maybe it would help to prevent a situation like this:

Ally with very low health fights with Zilean ult on him --> ally dies --> ally revives with considerably more hp than before

I guess this situation wouldn't happen much in higher levels of play, when people know to wait out Zil's ult and when small, unfavorable (for the enemy) skirmishes like that don't happen much, but it's the example that popped into my mind.

Tell me what you guys think!

[slayer-pantheon-popcorn]