They are handy for when there is zero access to using a box, and
there is no way to get a ratcheting tube wrench (Cam-Lok) in the right size on it, and
you can save time and effort in spinning a fastener, and
the fastener doesn't lend itself to being spun by hand quickly, and
it also helps if gravity helps you run the fastener down by quick movement without gripping firmly.
I was glad to have one for a door hinge spring compressor tool.
A quality set can be handy for a variety of open-end wrench tasks, if you're not a ham-fist who has to tighten the piss out of everything due to early childhood maternal conflict.
The external ring protruding from the 12pt box end on the SO SRXM10-19 version can come in handy; I think it's probably the same as their regular combo wrenches. It will reach into a slightly recessed hex on a stud that is not able to be accessed by a Craftsman combo, or a socket due to length.