I just went to Japan for a week and a half with a carry-on and it was just fine. In fact, I could have left behind two of the long-sleeved shirts I brought.
Really, up to a point – which for me is 3 days underwear, socks & undershirts and two outfits to go over them – the less you bring the better a vacation you'll have.
Next time you're at the airport just watch the people claiming their luggage. I sure hope some of those people are actually moving to the country they're arriving at because you shouldn't need a bag the size and weight of a coffee table to get you through a vacation. Who looks oppressed and in pain? The Giant Bag People. Who looks excited and adventurous? The ones walking past baggage claim on their way to the exit because they have all their stuff.
(Oh, and that War On Moisture, don't bring any liquids or gels thing? Just get some travel size toiletries when you get there. You can squeeze the first dose of toothpaste into your brush so you don't even have to worry about it the night you arrive. Just go out in the morning to explore a little & shop and then come back for your shower.)