The problem is DTD doesn't have a lot of parking to begin with. And all the people using it to avoid parking at the parks. Plus FL Residents passholders don't get on-site parking any more, you have to get a regular AP.
When Disney Village opened they did run buses between them, and into the DTD days. But if people are going to use it for parking, and then the people who are going there later in the day to shop can't park, there really isn't any reason to make it easy for them.
II'm really kinda surprised they tried it last year. With the Disney Springs construction starting up, parking was already a mess, unless they were thinking people would pay to park at the parks and take the bus to the mall (unlikely in my opinion) I don't see any reason to try it again.