Every ounce I have cut has made my trips out more enjoyable. I'm not putting so much energy into carrying a load as I am paying attention to my surroundings now. And the second day pains are not as bad.
If I have a backpack that weighs 6lbs, and get a new one that weighs 2lbs, that could either give me 4lbs extra I could carry more 'suitable' eating goods to eat a more refreshing meal, or more 'luxurious' sleeping gear to get a better night's sleep, or just that much less weight that I don't have to tote around. And it is good to have a weight ratio of pack weight to body weight. I think it is something like 25%, or close anyway, that is suggested. I am fairly thin, so that kind of lowers my suggested pack weight.
I just notice, more than anything, that I am not as beat and exhausted since I started carrying a lighter load. I have more energy and can go longer and further with a lighter load. I can go faster and have so much more balance and agility with less weight on my back. Before I cut my pack weight down, I was carrying around 55lbs for about 5 days. Now I carry about 32lbs for 7 days. Amazing how much saving an ounce here and there will save you in the long run.
Here's a cool tool to use for selecting your gear for trips, and finding out how much weight you will be carrying:
Gear Weight Calculator