Chuck, I'm with ya 100% on AR15 applications.
The KNS non-rotating pins ARE of benefit on M16s, though. In full auto, it's easy for the hammer to rebound too far and impact the disconnector, transmitting enough energy to egg out the pin holes. This is fairly common with Colt 9mm uppers, and while less frequent on 5.56, I've seen it in most all applications.
Usually the hammer and trigger pins will break first (and often the gun keeps keep running on the broken halves, which unless you notice quickly can also egg out the holes), but I've seen several '16s with oval holes that had to be drilled out and bushed, or switched to Colt large-pin internals, even though the pins did not break.
As a result, a lot of registered-receiver owners are switching to, and happy with, the locking pins, because they distribute the forces evenly over both sets of pin holes. (And since all transferable RR's were made pre-1986 and have been fired a lot over the years, the tolerances have loosened enough that locking pins work fine.) If you're trying to preserve a worn $8k lower, they make sense.
YMMV.