It's too bad that some people "work" the system to avoid parking costs. However, Disney does encourage guests to use WDW transportation to reach all areas of the WDW Resort (after all, easy access encourages more spending in their shops and restaurants). Maps available in the parks tell you how to get anywhere within WDW via the transportation system; and the following is from the transportation FAQ's on Disney's own website. (Note that ferry service from OKW to DTD is specifically mentioned)
Q: What is the best way to get around within the Walt Disney World® Resort?
A: There are many modes of transportation within the Walt Disney World Resort, including Bus, Boat and Monorail. A rundown of transportation within the resort:
By Bus:
Most areas of the Walt Disney World Resort are accessible by bus from other areas within the Resort, including Theme Parks*, Water Parks, the Disney Resorts and the Downtown Disney® area. Buses travel on routes throughout the Resort and do not provide direct service between all destinations.
*Magic Kingdom® Park is not accessible by bus from Disney's Contemporary Resort, Disney's Grand Floridian Resort & Spa and Disney's Polynesian Resort. These Resorts provide monorail transportation to the park.
By Boat:
The Magic Kingdom® Park is accessible by water launch from Disney's Contemporary Resort, Disney's Grand Floridian Resort & Spa, Disney's Polynesian Resort, Disney's Fort Wilderness Resort & Campground and Disney's Wilderness Lodge. The Disney ferryboats connect the Magic Kingdom Park to the Transportation and Ticket Center (adjacent to Magic Kingdom parking).
Epcot® and Disney-MGM Studios are accessible by boat from Disney's BoardWalk Inn and Villas Resort, Disney's Yacht Club and Disney's Beach Club Resorts and the Walt Disney World Swan and Walt Disney World Dolphin Hotels.
Downtown Disney® is accessible by ferryboat from Disney's Port Orleans Resort and Disney's Old Key West Resort.
By Monorail:
Disney's monorail runs between the Magic Kingdom Park, Disney's Contemporary Resort, Disney's Grand Floridian Resort & Spa, Disney's Polynesian Resort and the Transportation and Ticket Center (adjacent to the Magic Kingdom parking lot). A connecting monorail takes Guests from the Transportation and Ticket Center to Epcot.