Uhhh One advantage to the soft carriers
They love their carriers. Not as much after recent traumatic events (emergency evacuation during a fire, and moving) but they will eventually sleep in them or on them if I leave them laying about.
I do sometimes get a little worried about them getting bumped, or tripping etc. I've been very fortunate though. And since there is just one of me I do love the shoulder straps, so I can carry them both at once. With these carriers the kitties can still be close to me through the mesh. The Sherpa bag I have is much sturdier than the other more generic one, it tends to retain its shape better (the green bag on the left).
Only other issue, Shinobi (the black kitty) can open the zippers if I zip it to the bottom. She's gotten her whole paw out once. But I usually let her stick her head out the top because she likes to see what's going on and interact with people, and I don't know how I could do that in a hard carrier without letting her out.