Facebook isn't a retail site, it makes sense that you would need to login, because it's what's customize the site to you.

I think the complaint about login are on sites where it can't make any possible difference to what you came to do. Reading an articles or buying sausages should require a login, because it can't possibly contribute positive to the experience to add the extra step.

Honestly I believe that's why pay-walls doesn't work. It's not the at least some people won't pay, it's just that the processes of having to login to access something you paid for is reducing the appeal. I have a subscription for the Economist, I never use the online content, because I can't be bothered to login. I can't remember my username, or my password. It just because a hurdle and in the end I'd rather not deal with it.