While I don't disagree entirely with you in that this and other reviewers might be trying to convince us we need to buy a thing, I would like to disagree about the usefulness of this device. This reviewers uses are not using this device to its fullest. [ which is the case with many products, so can't blame them for that entirely ]
If you are a power user or you need to have your hands free, then this can be worth the money. If you are a make up artist as only one example and are making tutorials then being able to use a few keys on a footboard makes sense. Basically, any use where you need to use the keyboard and have your hands free makes sense.
Another use is if you are a power user and you already use a bunch of multi-key shortcuts and you are tired if dancing around with your fingers. You can make one or more of the foot pedal buttons a modifier key.
Obviously for a streamer having your hands free to gesticulate like you are a spineless puppet as you digital zoom effect in and out with your foot pedal to make your video "entertaining" is another thing you can't do with a keyboard.
Yeah, this is by no means a mandatory item, but for those that it can be useful for, it can be useful.
That this product costs so much more than the competition is another point of contention, but heck, I have purchased thousands of dollars worth of mouses, keyboards, graphic tablets, and such over my lifetime. Paying 40 dollars more than alternatives can certainly be worth it.