They aren’t motivated by it. They’re a result of it. Practically every rule or standard in the book can be traced to a crash. Mode C veil? Aeromexico 498, 82 dead. Radio comms standardization? Tenerife, 583 dead. CRM: United 173, 10 dead. Altitude requirements while being vectored to an approach (91.175(i)): TWA 514, 92 dead.
I could go on.
The answer to “why can’t we just” in aviation is “because people died.” The FAA doesn’t make rules just to make them. They make them because aviation is unforgiving and it will kill you and your passengers if you screw it up.