[2023] Seriously, why does K'Sante Q cost 15 mana?

K'Sante is a Tank/Assassin/Bruiser/Mage/Marksman that has Unstoppable, a Shield and goes over walls, has Airborne, and the cooldown is only 1 second too. The W CD is even refreshed when he transforms. He has true damage on his passive. Then, when he stacks Armor and MR, he gets Ability Haste too, Ability Haste to his Q, and his spell casting speeds up. Then, he has an AD ratio to help him trade and clear the waves better.

With all of this, why does his Q cost 15 mana? Why does he even have such a mild inconvenience in his kit? Just make it 0 mana so he can trade better against the other laners because right now, he isn't killing the opponents fast enough.