The only time I used one of these hook blades was to cut roofing where I removed part of the ridge shingle course to install a ridge vent. It was a pain pulling by hand. This would have made that and easy task.
For years I thought these oscillating saws were a non needed tool. But when you can plunge cut straight down in to oak hardwood flooring to install a new floor vent, and end up with a rectangular hole to the size you want, it really was a worthwhile tool. I did burn my harbor freight saw up plunge cutting a 2x4 for 32 inches, just too much time spent where I exceeded the duty cycle of the saw motor.
The other place they are handy is under a sink cabinet, where you need to enlarge or make a hole for the plumbing drain and supply pipes, you can get in where it's too tight for any other saw.