Denise R. Jacobs' presentation at the 2010 Web Design Conference emphasizes the importance of user experience through CSS3, highlighting its benefits like easier visual effects implementation, while acknowledging challenges such as uneven browser support and code bloat. The talk underscores the need for a balance between graceful degradation and progressive enhancement to ensure usability across diverse browser environments. Jacobs advocates for integrating CSS3 to enhance design quality and user interaction, while also preparing for the inevitable limitations faced by users with older browsers.