I believe that over time, there should be a new concept, Champions having 2 ULTIMATE CHOICES!

For example, I'm a thresh player. The box ultimate or lets say a new ultimate called

Slaughterhouse: Chains an enemy to their location for 3.5-5 seconds, and they cannot use any abilities or summoner spells. If they attempt to walk out of the chain, they are pulled back to the slaughter.

Or as Leona instead of her solar flare ultimate, maybe a new one to choose depending on the situation called Excess Heat, over time, leona using her abilities passively gives her ultimate heat. Which when she activates her ultimate, depending on how much heat is excess, she can produce a shield that damages nearby enemies slowly over time also on to who she places.

I don't know, I think if all champions had A CHOICE between two ultimates, there'd be so much counter play and decisions to improve the gameplay and feel.