I'd never heard of System1/2 before, but it makes a lot of sense. Sites that are similar to the FB timeline, like Pinterest (which I recently signed up on to try it out), also give me that same sense of having to 'pay attention' more. It becomes more of a novelty instead of something that I'd want to use all the time. I think that is part of the popularity of sites like Craigslist and Hackernews, which present the information in an easily scanned format. They both fall into System 1. I think that as I do UX design for my site, I'll keep this in mind.