The takeaway is that it usually carries no penalty to carry too little luggage. Imagine: you're traveling to Thailand on vacation and you forgot to pack a beach towel. Do they sell beach towels at the beach in Thailand? Ya betcha! How much will the price of a towel weigh, relative to the total price of your vacation? Zero! Now make your choice: should you bring a towel from home in that situation? My take: no. On the contrary, by all means buy one there:
1) you travel light,
2) you can bring home a new towel full of nice memories,
3) if you finally decide not to bring it back home, then leave it there and make someone happy!
Another exercise: you're traveling to London for 3 days on business. Should you bring an umbrella?
My take: again, no! If you answered yes, perhaps you were fooled by the word London. It does not always rain there. And if you're on business, you'll probably be indoors all the time. The only chance to get wet would be during the ten seconds between your taxi and the hotel lobby.
By all means, only pack an umbrella if you're sure that it will rain most of the time, AND that you will have no choice but be outside for a while AND that it will be real rain, not just a couple of drops AND that you will have no way to borrow one AND that you will have no way to buy a flimsy one there for 2$. That means: practically never.
Disclosure: yes, I do buy flimsy umbrellas while traveling. Last time was in Moscow and the conclusions are: it was extremely easy; you do not even need to know the word umbrella in Russian; and it ended as a gift to the hotel maid.
In case you're wondering, I still have that Beijing shirt. I really like it, and every time I wear it, it takes me back to that Sunday afternoon in the big city...