"Is it because Glocks have made people think automatic pistols do not need safety catches?"
The R51 safety isn't nearly so easy to depress as 1911's; it's a distinct click and about 1/8" of movement. It also, in its present form, has a
very aggressive sear interface that makes for a very "hard" trigger break (you have to cam back the hammer a good five degrees or so at mechanical disadvantage before it lets go). Were the sears tuned for minimal engagement and butter-smooth slip (there's no indication the design geometry wouldn't lend itself to
very fine sear jobs if desired) I would agree that more measures would be needed for drop-safety.
There's even a theory that the reason for the cheap/skeletonized trigger was to reduce its weight in order to thwart discharge in the even the gun fell, hard, right onto the quasi-shrouded safety lever. A heavy trigger
could pull itself in such a scenario without binding up on a dedicated trigger safety like the Glock's.
I think that if it's possible, a good alternative might be ditching the long firing pin travel and heavy return spring for a true mechanical firing pin safety, for several reasons:
1) Ditch the horrible disconnector setup they have now, and use a bolt-mounted firing pin safety plunger, deactivated by trigger takeup, to also disconnect the trigger bar when shifted out of battery (would instantly make the gun safe against out of battery discharge, and greatly improve slide pull)'
2) The unique way in which the gun operates would cause the slide/bolt to shift backward in the event of a drop on the safety lever, harmlessly disconnecting the trigger before it could release the sear under its own weight (aided greatly by the aforementioned lighter slide pull)
3) Present only a single point of contact between the slide/bolt and trigger bar perform the disconnect, making the timing of the hammer drop and disconnect far simpler (closely related to number 1)
4) True, positive, muzzle-down drop safety instead of spring + pin travel that causes primer dimples (and can be overcome by sufficient force)
4.5) Alternately, recess the barrel slightly inside the slide nose, so a drop on the front would first push the slide out of battery
and cushion the impact; in that configuration, no firing pin safety of any sort would be needed
5) Mechanical drop-safety in the direction of the trigger would allow the sear surfaces to be far more neutral, for a shorter, lighter trigger pull.
Call it a
"Kinetic Safety" if you want a buzzword, Remington
TCB