It's interesting to read these passionate opinions about the proper purpose and use/misuse of the Engine Stop Switch (ESS) / "kill switch".
Personally, I fall into the category of a daily user of the ESS.
One reason: habit from riding dirt bikes. On a dirt bike, I always press the kill switch to stop the engine because I like to keep both hands on the grips while the engine is running. I feel the same way when I am on my CBR.
To start the CBR, I turn on the key to "on" with the ESS "off", to let the computer / dashboard boot up. I use that moment to review the display. Then I flip the ESS to the "on" position, which runs the fuel pump and I presume enables the ignition system. After classically waiting for the fuel pump to stop and the yellow light to extinguish, I press the starter button.
To stop the bike, I flip the ESS to "off," stopping the engine. Then I take my hand off the grip and turn the key to "off".
Some possible advantages I see to leaving the bike parked with the ESS "off" and/or getting in the habit of integrating it into the start/stop procedure:
1) If you forget and accidentally leave the key in the ignition, leaving the ESS in the off position might fool/foil a thief who forgets to check it in his haste/anxiety.
2) If you are not in the habit of flipping the ESS to "on" when you start your bike, you could yourself be stumped if a mischievous passerby flips it to "off" while you're not looking. I have known of at least two people whose bike "wouldn't start" when in reality the ESS was off and they didn't realize it. In one case, it caused embarrassment for a few minutes. In the other case, the person had their bike hauled in for service only to discover that nothing was wrong with the bike.
3) To help keep the ESS switch contacts clean. I have to think that most modern switches are designed with some amount of self-cleaning or wiping action built into their operating motion. If the switch just sits there in the "on" position all the time, the contacts could just oxidize and over time possibly become intermittent. I just ran across an advertisement for an older Honda that said "Runs great. Only issue is that sometimes hitting a big bump will cause the engine to shut off." I wondered if it could have been dirty/intermittent contacts on the ESS.
4) At the gas/petrol station, as usual I stop the engine using the ESS. At this point the key is still "on", which allows me to read and then reset the trip odometer while the engine remains safely turned off. Conversely, if I used the key to stop the engine, I would then have to immediately turn the key back on and wait for the computer/dashboard to boot back up so I could fiddle with the trip odometer, or else wait until I'm ready to leave to turn the bike back on to read and reset the odometer. However, I like to do all of my fuel mileage reporting (via texting to fuelly.com) after fueling and before I turn the bike back on.
I'm not advocating one way or the other, just offering up what I do and why I do it. If I have any problems with the reliability/longevity of the ESS, I'll report it.