Naval missiles need shipboard design work

Why did the US Navy and Royal Navy prefer purpose-built naval systems while the Soviets often adapted land-based ones?

Shipboard systems had to survive salt water, handling, temperature variation, and naval logistics, so even a similar weapon needed substantial redesign.

Naval weapons cannot be treated as simple copies of land-based systems. Shipboard weapons face salt water, temperature changes, handling constraints, and logistics that alter missile casings, seals, electronics, and support equipment. Carrier aircraft face the same kind of adaptation problem. A sea-based system needs a tougher design for a harsher operating environment.