Works better on more screen sizes. All standard web tech; no flash/Java/browser specific things.
Less clutter and visual distractions once you block adverts. Also much much easier to navigate with a consistent design guideline vs having every page randomly assembled with no oversight. Standardised components and design also makes larger websites possible without having to manage 1 billion pages and elements.
The facebook pic in the top banner is cool how it fades.
Why is modern design better? It is just the mobile aspect?