The Web changes every day. As new technologies and methodologies arise, former industry standards fall by the wayside in favor of more efficient and effective tools.
Staying up to date with the latest trends and best-practices of the Web helps you stay relevant and ensures your work can stand up when compared to sites with ten times your project budget.
One of the best ways to improve the your work is to take the time to see the envelope-pushing things your peers are doing. Web-focused conferences (such as the phenomenal Converge SE 2013, hosted right here in Columbia, South Carolina) provide this opportunity in spades.