Will is required to create and maintain strong constructs, but the constructs are only as good as one’s knowledge and creativity. There’s much more to bring a Lantern than just will.
Apathy or indifference are not willpower. Real willpower is the ability to feel pain and not let it consume you. To have hope when you’re afraid. To put the needs of others before yourself. To love your enemies instead of hate. Will is what balances the strongest emotions within us.
I think a green lantern with absolute will would be unstoppable image the rest of the lantern corps emotions with absolute power for example a red lantern with absolute rage or a blue lantern with absolute hope