Re: Safety Lesson? What is your practice now?
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Mostly slow down and keep both hands on the beast until it's fully stopped and can be set down on the bench in a safe fashion. I've caught myself cheating with the router spinning down a few times as well and this mostly put a stop to that also 
I've also since moved it to a grinder witha "trigger" switch so I can more easily practice trigger finger safety as well (I can also get a better hold on the grinder with different angles - the preference here seems to have a lot to do with specific usage and hand size so ymmv on any specific recommendation). I don't really think that a slide switch would be necessarily better safety wise, although it may well have prevented the accident I had, the risk of it not stopping on release is imho perhaps somewhat of a worst problem overall.
The Kutzall is definitely way less grabby than the chainsaw style cutters so I still use it some where it makes sense. I did have a few months of reflection and more moderated use of hand tools but it's a super convenient way to remove a whole lot of material in a hurry in certain shapes (I was making a very large spoon ~36" long, 4" bowl when I had my oops). I haven't watch Stumpy's oops, but some people who are more comfortable than I am with those cutters had a lot to say about how he was using it, the upshot was that it was kinda like using the upper tip on a chainsaw bar and kickback is basically guaranteed (plus he apparently didn't have a very good hold on things). So like anything like this there are certainly "safer" (if not absolutely safe) ways to use them.
I also have a selection of angle grinders with other grinding and cutting implements on them. They're also treated with a lot of respect, especially the friable grinding wheels and cutting wheels as they can shatter surprisingly easily and have a tremendous amount of force. It's one place where imho a full face shield is mandatory.
An acquaintance recently had a very bad accident with a chop saw with a cutoff wheel that exploded, it took large chunks of bone out of both shins and he suffered quite an amount of blood loss. This was a fellow who worked in iron working for pushing 50 years now (recently retired just a few months before this happened). He's walking again ~5 months~ later but it looked painful. He was also really lucky it didn't get him up higher. Just the week before I learned about his wreck I was helping a friend cut up some 4" tube steel with a similar rig and he was squatting half spread leg in front of the saw cutting - to which I expressed my discomfort. The next week the fellow who had the wreck came wheeling(still in the chair at that point) to my friends place, so I got a bit of "and now I get it wow!!" afterwards
I'll forebear any discussion of tractor PTO accidents, growing up on a farm a few neighbours had a rather bad time :/
So yeah any fast rotating thing can definitely get you. The more distracted, tired, or complacent you are the more likely it is to happen. Understanding how they work and where the danger zones are before getting started is very important.. as well as (in my case heh) a basic understanding of physics and centripetal forces
. The other is equipped with a diamond blade for cutting masonry, including plaster, concrete block, bricks, porcelain bathroom tile, slate pavers, etc. Most of the time, it is installed in a Harbor Freight gizmo for chopping rebar and metal pipe. Just thinking about it raises my hackles.