Capacity means freedom
I just got back yesterday from a three month tour. I had four panniers, a handlebar bag, and a lot strapped to the rear rack. It was heavy, no doubt, but not as much as it looked like. Had a ton of warm things, both to wear and sleep with. In fact, since I'm fairly big, one of my sweatshirts couldn't even fit an a bikepackers' setup, to say nothing of my other sweatshirt, sweatpants, extra blanket, and multiple pillows. None of these things weigh very much. I don't even want to think about how I could have survived the last month without, however.
I also don't know how I could have brought enough supplies up to Joshua Tree without my huge capacity. I would have had to go down the mountain to the store every day. Once I got my hands on enough water, didn't need anything for four days. Even though it was super difficult to get all those things up the hill, it was easier than doing it multiple times. Plus, I was able to bring things from further away, which meant much cheaper than the store in town.
I know one thing, I couldn't have done without any of my warm stuff. I would have never went to the high desert at all, but rather been forced to stick to the Southern Tier and take my chances with the dune buggiers who congregate the desert that time of year.