My philosophy is to reduce weight but not be fanatical about it--though I do admit that lighter almost always makes for more pleasant cycling. It's just nicer to have less weight to push around.
Here's an example of saving weight in, for me, a really good way: I stopped using a trailer. I did a ride from California to Arizona towing a Burley Nomad--great trailer, super convenient, no flats, no problems. I can totally see why folks like trailers. But when I looked at the panniers that my German recumbent could use, I calculated that I could shave at least 10 lbs.! That's no joke on climbs. I sacrificed some convenience, but the increased climbing ability and better aerodynamics in windy conditions were the clinchers.
For my cross-America ride last year, I ultimately chose a Pepsi can alcohol stove, which is about as light as they get. I cooked the vast majority of my meals, made coffee every morning, often a second cup later in the day--great!
I splurge in weight with sleeping gear. I really want and need a good night's sleep, so I carryied a 2" thick, full-length Thermarest pad with integrated camp chair--weighed about three pounds. But man, was it sweet. Pull into camp, set up the chair and kick back for reading, cooking, journal writing. I've since acquired a Big Agnes air mattress--lighter, more compact, more comfortable. The only drawback is that you get a little light-headed filling it up! Setting up the Big Agnes chair is not as convenient as the Thermarest, however, but it seems okay. I think the BA combo is about a pound lighter than the T-rest.
For me, in most settings, a tent is essential in order to avoid insects. Westinghouse recommended a tarp, which is fine, but I can't imagine what that would have been like in the mosquito infested Midwest last August. I also like the idea of a little cave or shelter to call my own, a sanctuary that sets me apart for a while. When conditions permit, however, I love to sleep out under the stars. As I got into the Southwest in October, I had a blast laying out the tarp and flopping out in the open--no bugs, clear skies, can't beat that. My tent is a Sierra Designs one-person model, can't recall the name right now, and it weighs about three pounds. I go super light with sleeping bags and carry a sub-two pound 20 deg. F. down bag--very compact, too!
Leave the cast iron gear at home, and you'll be fine!
The more important thing is to realize that you don't need the best of the best. People get by and have wonderful adventures on all kinds of gear. Mostly you need a reliable bike and a way to carry gear so it won't fall off. Get out there and ride.