We often camp with friends - so can't just retreat to the tent. And it's often cool at night (or downright cold sometimes), which makes sitting under the tarp without heating uncomfortable. And when we're with a group, the campfire IS our entertainment.
We rarely take a lantern. The times I've taken it, we didn't use it.
But this time I will be comfortable in my sleeping bag in the tent when it rains in the evenings.