The entire design would need to change to meet safety standards. I don’t know that the ease of assembly and cheap low cost would survive the safety requirements.

A lot of the complexity of modern vehicles encompassing not just drivetrain but also exterior design is to squeeze fuel economy from a stone. The shape of the Willy’s isn’t aerodynamic and that’s putting it mildly. Modern standards for body panel tolerances raise component costs. Full time 4x4 is awful on paved roads and terrible for fuel consumption, so we would now use a transfer case or a AWD system, which add cost and complexity. The simplicity of the suspension design made it a death trap at speed - good for off road, no good at 70mph.

My point is that as much as I want a repairable, simple thing (car, computer, etc.) we’ve developed so much technology that even when a thing is designed for repairability, it’s going to need specialized skills to some extent - can’t fix everything with a hammer anymore. Might need a torque wrench.

The current wrangler is an idea of what a modern Willy’s would be like. It’s going to be a $40k vehicle.

ETA - Ineos Grenadier is a modern take on the classic Land Rover. Similar concept, similar departure from simple an cheap.