A lot of gravel gear is designed so that you can use it off the bike as well as on. That's a nod to the option of going long that's a feature of gravel riding. So you can always shed your bibs once you get to your stop and wear your outer shorts on their own to slope around camp or a lodge.
If you're bikepacking you probably don't want to be locked into tight, sweaty lycra when you're setting up camp or resting at the end of a long day. It means you won't look out of place at a coffee shop or wandering around a grocery store to stock up on provisions either.