People spend way more time in Facebook than email, and (paradoxically) it's way easier to get them to like a Facebook page than to enter their email address in a form and hit submit.

So yes, email is great, but marketing is multi-channel or pointless. Facebook is the single biggest channel out there.

Yes, you have to invest some $$ in Facebook to get above the noise floor, but again: that's marketing. Email costs money too. Nothing comes for free.