With all the tree hangers around, I thought I'd ask... Why are hammocks so great?

Some background... I've always been a tent or tarp user, and have liked it just fine. The ground is hard, but I carry a 13.8 oz thermarest to help. I enjoy tarps because of the free space and air flow. A hiking partner of mine does have a Hennessey hammock, and although I haven't stayed in it overnight, I did check it out. It seemed cozy and had plenty of protection. So, I've read through Sgt Rock's hammock information and enjoyed learning, but I still have some questions.

Being weight conscience, the lightest hammock that I've found is the Hennessy Hyperlight (26oz.) - and I'm not even sure the tarp is big enough to live under on a long walk.

I know that different trips call for different gear, but it seems that hammock lovers stick with their systems all the time. Is the sleep so much better that the increase in weight is a non-issue? That seems to be my main question.

Please give me any other perspectives that I may be missing.