I need some comfort to sleep otherwise I'm more and more tired on the trail, I get up later and later and get cranky and then I just frigging stop and go back home.
There are situations where a tent will be more comfortable: a tent provides protection from the wind absent natural barriers, a tent provides a refuge from biting insects, etc.
In many situations, the comfort provided by a tent is more mental than it is physical. The full enclosure of a tent provides comfort to people who worry about critters crawling over them in the night. Some people just feel more comfortable when fully enclosed.
All this said, it does take more expertise to sleep comfortably with a tarp. Site selection is more important. There are several ways to pitch a tarp and the best pitch to use depends on the situation. Tarps are more fiddly to pitch.