Yep, just happened to notice this. It's true for me too.
I used to pack heavy, but when I started traveling for a living, I realized that the old ball and chain suitcase packed full of stuff I never used needed to go.
Since then, it's just a carry-on for the week - sometimes as long as 2 weeks. They have these neat things called "Washing Machines" in hotels and laundromats that I have learned to use while traveling with one or two changes of clothes.