An "R" clip, or "hitch" pin can be accidently knocked out.
For the record, I wouldn't put one on an aircraft, a component that won't be removed, or where it can be accidentally knocked out either.
Having said that, I have 'R' clips on my pegs (swap custom for stock ones on long trips), and only way you can remove them from that location is with pliers, and it's still not easy (but you have to get the right ones though). I also use them on bikes with a cotter pin on the rear axle nut, by the way.
But your point is well taken. We need to use good judgment when making changes to our bikes. But unfortunately, good judgment varies from person to person. I, for instance, wouldn't remove a pin from my clipons to rotate them outward, but others think is not big deal. Others, like you perhaps, probably think I'm crazy for using 'R' clips on my pegs, but I think they're as safe as cotter pins in that location, but much easier to remove.
The good news is none of the above options is unsafe, but for the sake of comfort or convenience, we sometimes go from the safest to a still safe but not the safest option. And sometimes you can have both safe and unsafe conditions with the same item: namely, TIRES. I'd consider unsafe (almost suicidal, really) riding on Marathon 880 tires the way I ride, but for folks who tour a lot and hardly ever lean can be perfectly safe... and more convenient, as they last twice as long.
Finally, I always keep an open mind reading forums like this, and have changed my mind on many things; that's why I like a lot reading forums, especially with a new bike, or a new procedure, or something I haven't done before; there's a wealth of knowledge once you know where to look for it. Have a good one gang.
JC