The downside of low tech solutions if many people touch it (i.e. not just the janitor or rostered staff) is that someone can still add their shared mug to the dishwasher just after a cycle's complete, causing the entire batch to be considered unclean. Or in your example, someone deciding to flip the sign but not emptying out the dishwasher.
Then again, these are little things that people have learnt to make do and just live with, and I'm not sure it's worth paying 2x or 3x, or even 20x the price just for fancy feet, like what the article thinks people might do with a fancy oven.
That doesn't help, however, if users are lazy and don't unload the dishwasher after opening it to grab a clean plate or whatever.
It's a nice feature that can be added with existing sensors and one line of logic in the uC. Another one I noticed recently is garage door openers with the photo transmitter/receiver ('beam') to stop the door if someone blocks it can use that same beam to turn on the light if broken when the door is up. Handy if entering a dark garage from outside.