You can have all the human contact and "it's 6pm - want to go for a beer?" easy socializing that you get from being in a busy office, but simultaneously keep almost all the flexibility and the lack-of-constraints of working from home (...almost - there's usually an expectation that you wear clothes).

In many ways it's even better than office social contact: it decouples that socializing from your job. Want to change company, but keep hanging out with the same people every day? Want to switch offices and meet a whole new social circle without changing jobs? Want to go out from the office for a drink after work with your 'colleagues' with no need to avoid personal topics or keep things professional with your boss?

It does require leaving the house, but for almost everybody there is a coworking space that's significantly quicker to get to you than your current office would be. If you're in a major urban center, you probably have 10s or 100s to choose from. For me, it's a dramatic improvement on both the alternatives.