I absolutely need this power switch. Android bluetooth gets buggy sometimes, and I have a habit of ending up in places that seem to be noisy or otherwise less usable with 2.4 GHz. Being able to power cycle my devices to get them to rejoin quickly is really critical to my ability to use my stuff.
Also, I keep two and have one as a spare in my bag. Keeping it off makes sure my battery stays unused, and that a random press doesn't wake it up and send random keys to my phone.