"The brains on stalks model works, you really don’t need much more from an engineering point of view."

Have you known many engineers? My late father-in-law was one, and I've taught a good many of them. None of the ones I've known would have settled for "it works" as being satisfactory. I've talked to a lot of them about this, examining living beings from the viewpoint of engineers, and all of them say that life is what they call as 'bodge job'. One of them even called it 'bodgology' as opposed to 'biology'!