I think it is fair to generalize that the greatest benefits in general came from the continuous development of lighter and stronger fibers, starting with glass fiber, then better glasses, then aramid, carbon, UHMWPE, Vectran, PBO, etc..

Here is a list of developments made possible due to the new or improved fibers.

Sails:

-Lighter sails with better retention of shape.
-Square top mainsails
-Asymetrical spinakers (in part)
-Longer lasting cruising sails

Spar

-Lighter Carbon masts, booms and bowsprits
-Lighter and cheaper syntethic shrouds, backstays and halyards

Hull

-Cheaper hulls (glass)
-Lighter and stronger hulls (carbon, kevlar, etc.)
-Lighter and stronger beams (carbon)

Foils

-Lighter rudders and daggerboards

Hardware

-Lighter parts made of carbon

Ropes

-Lighter and stronger ropes, replacing stainless steel.

Cheers,
Luiz