No doubt that those photos show cracking of the cast aluminum. In the one's from Wingfoot, the short lines that run perpendicular from the crack illustrate filiform corrosion under the breached clear coat. In those photos, the corrosion is a by-product of the casting failure, not the cause. For the most part, the filiform corrosion is superficial and cosmetic. It does not cause structural failure. Casting defects, such as voids, cold shuts or inclusions, usually are the culprits.
If those were my wheels, I'd be on the warpath, too.