I think part of the reason for using wire was for fire proofing. The recording would be salvageable even after intense fires. Later recorders used plastic tap

I think part of the reason for using wire was for fire proofing. The recording would be salvageable even after intense fires. Later recorders used plastic tape but also have a water vessel. As the water boils it keeps the interior from going above 100C - until it boils away. The recorders are rated for maybe 30-60 minutes of direct exposure. Recent recorders use solid state storage and, still, water to keep the internal temperature lower.