Reason 01
Depth beats surface
A cream works at the outermost layer. 630nm light reaches roughly 2mm, which is where collagen and elastin are actually made. That is the layer holding the under-eye taut, and nothing sitting on top of your skin ever reaches it.
Lee et al., 2007: red LED phototherapy measured up to 36% wrinkle reduction and 19% higher elasticity. Studied at 633nm, ours runs 630nm.