Rigify's neck bones

Rigify has two DEF neck bones but they move as one. Is this by design?

I’m trying to figure out how to make those two bones work as a more natural (or less stiff) neck rig. However, the whole control-bone-DEF-ORG-MCH-tweak-bone relationship is pretty tangled.

I’m thinking of deleting the whole head/neck setup after generation and making a custom one, but with all the scripted features I fear breaking something. Even worse, that the damage won’t be immediately visible.