Gold is an excellent electrical conductor and is corrosion resistant.
The compression spring will actually increase the life of your jack by providing a better connection. Planet Waves' engineering staff has conducted test after test, jamming the plug into and out of guitar jacks for thousands of cycles, and no damage was caused to the jack or the connector. When not inserted into a jack, the compression springs are slightly larger in diameter than the inside diameter of a normal jack. When inserted into the jack, the springs compress and conform to the inside diameter of the jack. The springs stay compressed and under pressure, making a far superior ground connection, and holding the jack in place more securely.