RT-Mart decided to replace my bag with a newer model. It basically is the same, except one piece of fabric outside changed colour from blue to orange.
Hopefully this one will stand up a bit better. Given that both straps function properly, it is a lot more comfortable to wear on my back.
I still haven’t figured out why the retracting handle for pulling it on the ground has a curved rather than a straight frame. It seems like it makes it more expensive. It would curve the back of the bag more natural to fit against the average spine, but given there are other bulky pieces of the bag in the area, I doubt it makes much of a difference.
In any case, I am glad to have a larger bag that I can throw my things in, and I am glad that RT-Mart stands behind the products they sell in Taiwan.