I agree with both Gideon and PapaSmurf. It really depends on where you live and what works for you. I have friends whose main goal in life is to push their pack weight limit down to the bare bone minimum. But in the tropics even they can't forgo the integrated bugnet.
The design of the Darien (as the name implies) works very well in hot weather, without compromising protection. In tropical places such as the Darien or the Amazon regions, the bugnet adds a few ounces of weight, and what's worse, about 4 degrees Farenheit to an already warm situation. It would be great to do without the net. However you'd be insane to do that because of all the biting or stinging critters that could prey on you at night. Most of them are just a nuisance that won't cause more harm than a sleepless night, but some can be quiet and lethal, like the kissing bug that carries Chagas disease (a heart condition that gives you no symptoms until 20 years later when your heart explodes), or the skin parasite known as bott fly, whose larvae feeds off of your skin until it gets up to about 1/2 inch big, then hatches and flies away (tip: you can suffucate it with a piece of sausage); or the sandfly species that carry Leishmaniasis.
Let's put it this way, while campers in some parts of the world have to worry about bears, and all the stuff that comes with that, we worry about the little stuff that can kill us just as easily.
Incidentally, I was hiking in the Darien about three weeks ago with some friends. We picked a beautiful camping spot by the river. The problem was that everywhere we looked the trees seemed to be either too far apart or too close together for our hammocks. I finally settled for a spot that had some reasonable space between trees. I got out to pee at around 2am, and when I was about to jump back in the hammock. I saw a few hundred black ants crawling fast along my tarp and my hammock ridgelines. Apparently one of the trees I had picked was their home and I had squatted in their territory. I got in my Darien hammock making sure that no ants had invited themselves in. I programed some playlists on my iPod, and went right back to sleep. No way I could've gotten away with that without the bugnet!!!