Low Cost Carriers (LCC) sometimes weigh your carry-on bags, and I was so proud of the day that happened to me. My suitcase + laptop bag weighed in at exactly 7.0 KG, and the check-in agent kinda looked at it in shock.
While American Immigration & Customs is a breeze thanks to Global Entry, other countries can have long immigration lines (and elite status may not help you there), which is when I see people carrying their backpack for an hour or having to slide it across the immigration hall for an hour. The wheeled suitcase carry on saves your back while still being able to store plenty. Don't get a hardshell, get a fabric based suitcase as that will be lighter. I also often travel with airlines that I have elite status with, which affords me either less scrutiny or extra carry-on weight allowance.
Just need to plan when to book a suite that has a laundry machine, a hotel that has self-serve laundry, or a long stay where you can send your clothes to be cleaned overnight.