The only attribute UHMWPE has over steel is abrasion resistance and lighter weight. The material is not nearly as impressive as you seem to think it is. UHMWPE is soft, almost like a PE that has been impregnated with soap. That’s why it has great impact and abrasion resistance. But it isn’t a structural material. Dimensional stability, hardness, toughness, etc don’t compare to metals in any way. And it’s not optically clear either. Its best use case is for cladding on ruggedized consumer products. If you want a real structural polymer to make machine components out of, you need glass-reinforced thermosets.