The Scripture Is False And The Biblical God Is Dead.

[Astreja]

all it really demonstrates is that they're using a secondary pathway that doesn't correspond to normal visual perception but clearly is perception nonetheless.

What do humans need normal visual perception for if they can function without it?

We function better with it.  We can perform complex tasks more easily.  We can identify danger at a distance in environments where it's too noisy to hear someone sneaking up on us.

It may not be an outright need, but it improves our evolutionary fitness considerably.