The answer is quite simple, actually. To stand out.
More and more brands are working with bloggers every day. Can you imagine how many Word docs and PDFs they receive? Tons. How do they differentiate all of those files that basically say the same thing?
They don't.
But when you send them the perfect pitch with the link to your beautiful digital media kit, packed with graphics, stats and links to back up your credibility, you're guaranteed to make an impact.