But even on a simple blog, bounce rate is a useful stat. Many bloggers don't just want people to come from Hacker News and stay for one article, they want these visitors to click around to related entries after they are done reading. Bounce rate gives a good idea of whether this is happening or not (unless you automatically count almost all visits as non-bounce by triggering an event after a brief time interval).
Line 3435 (for me, I'm logged in) holds the answer.
blog.yourcompany.com isn't doing it's job unless it engages someone enough to share the content / comment / find out more about the product and on...
StackOverflow have established dominance in organic search and buckets of engaged users: not many sites are in the same position.
Track any other action a user takes in-page like sharing/commenting with a GA event.