Actually, most travelers are still big time pack mules...
But considering that hikers out in the wild carry just 10 lbs base weight or less -- travelers should be able to carry even less -- since shelter and bedding (i.e. hotels) are conveniently available and need not be carried!
Some travelers overload their packs because they feel better when they have everything at hand. While this might be important when out in the wilds, it's nonsensical when stores are everywhere!
To me, the flexibility of having everything at hand is dubious compared to the flexibility of traveling light and being able to just "get up and go" -- and making all kinds of unplanned stops just because you see something interesting. If you carry just a small bookbag, that's easy to do. But if you have a 90L pack on you, you can't go anywhere or do anything until you find a hotel and unload the darn thing!
Yeah, just like with hiking, turning yourself into a pack mule is no fun when traveling either -- and so unnecessary too!