Given all the luggage options and the evolution of design - I am surprised at the design of some bags. Example: north face base camp duffles. The carry handles on the extra small size do not loop across and join the opposing handle for one-handed carry. The medium size does. I would think the NF design team would have some basic luggage function rules to apply to their bags. So, it would be easy for a consumer to order this bag online only to discover this annoying fact later. It's fine if you are only going to use it in backpack mode.
It's another edition of the "it's not a bug, it's a feature! No, it's not a feature, it's a bug!" discussion.
This week I bought - and yesterday I returned - an Eagle Creek Tarmac 22 carry-on roller bag. I'm an Eagle Creek fangirl; my EC bags have proven to be nearly indestructible. That said, this latest carry-on had a "feature" that irritated me immensely. And, I'm not paying Eagle Creek prices to be irritated.
The "feature" on that bag that I hate: a hyuge and heavily padded laptop sleeve built into the back of the lid. The short version: it's poorly placed, accessible only by opening the bag, far (!!) too large for the laptops/notebooks/Chromebooks people carry today, and generally a waste of space and materials. That bag is already short on capacity given its size. Heaven knows how many more cubic inches of usable packing space were wasted on that "feature." Bag returned, money cheerfully refunded.
The presumptuous assumption with TNF’s XS and S duffles (I assume) is that TNF doesn’t expect the diminutive bags to be used for hauling 10-20kilos so the two smallish haul handles should be sufficient. If you need to move mass comfortably, you will get the bigger bag.
The REI Big Haul 40L could be seen has having a few flaws. However, after taking it to Scotland, I can say it worked well and met all of my expectations. However, I’ol be using the Patagucci MLC45 or Bihn Aeronuat30 next time. And even those superbly designed travel-specific soft suitcases have their weird features/bugs.