Yeah but "that" helps the gray hair syndrome of remembering to check.
It lets you know its happening automatically.
If you look at it they using a proximity sensor and that is where cost comes in. Its not a gimic.
Do you forget to turn on the lights when you go into the shop?
Do you forget to use hearing protection and safety glasses?
When I get set to run a tool that uses the cyclone I walk all of 10 or 12 feet (max) to the cyclone, bend over just a bit and "look" into the window......
if it is full, time to empty it, if it is NOT full, return to machine and cut stuff.
Next thing they will come out with a gizmo that sends you a text message if your cyclone bin is full, or calls your wife and gives her a recorded message.....
Sorry, I can think of a LOT more things that I'd spend the money on.
Now, if your cyclone is outside in a shack well, that is a very different thing, checking it would not be easy, so the sensor would be good for that, but if you cyclone is in the workshop.....
My opinion mind you, YMMV