You can walk from their resorts to the parks and all the shopping. (Well, except the new one they are building. I don't know if that will be in walking distance.)
I would love to see an improvement to the WDW transportation system. I know a monorail track is really expensive to build, but it always made sense to me to run a monorail to Animal Kingdom because they run on electricity and are very quiet, so as to not pollute with CO2 or noise anywhere near the animals.
Looking at the resort's layout and map, I don't really see any other areas to improve the transportation system. A monorail could be run to Hollywood Studios from the Ticket & Transportation Center, but in relation to EPCOT and Magic Kingdom, Hollywood Studios is tiny, and not worth the trouble or cost. At least not until or unless they really expand the park with Star Wars, CarsLand, a larger Pixar Place, etc. If Hollywood Studios were an actual destination park that took more than half of a day to completely explore, that could be an option to consider. I just don't see it.
Unfortunately I think what we have is what we're always going to have. It was poorly planned from the get go, with the thinking seemingly that they have all this land, so just build whatever, wherever with no forward thinking in mind. And it's such a shame. But there is still hope, and there are options available, should they choose to do it.
That being said, Robert's suggestion of the Epcot Resort Area as "downtown" makes total sense.
Tracy, if you're talking about the Cabana Bay Beach Resort it'll be connected to Citywalk via a pedestrian bridge being built over Hollywood Way, then the sidewalk along Hollywood Way down into the access area next to Margueritaville.
A good option if Disney wants to invest is a new downtown west of the World Drive/Epcot Drive intersection immediately north of Coronado. Would be interesting to turn into a hub with a shopping/entertainment area, large upscale hotel and a large convention center. Re-route the MK-Epcot line to hub here. It's also a short hop for a monorail to the Animal Kingdom. Use light rail to go to DHS with a stop at Epcot Resorts.
You can put Coronado, Blizzard Beach, and AK lodge on the AK run. Epcot Resorts sits on the DHS run. While water transport is fun, it is slow. Put a feeder line to MK from the Wilderness lodge, campground, Port Orleans, Key West, and Epcot. Put a separate feeder from AK, All Star, Wild Word of Sports, Art of Animation, Pop Century, and Caribbean Beach and DHS. The feeder lines also provide redundancy for every route.
The name Downtown Disney suggests it is a public oriented shopping center for Disney fans, while the Boardwalk is designed for resort guests near Epcot. I never felt the Boardwalk is comparable in any sense to Downtown Disney. They each have a different retail/shopping/entertainment mix.
Downtown Disney's main problem is oversaturation. There is only so much you can milk from the tourist market. It needs to attract more locals to visit. It probably failed with local residents unlike other locations especially in Anaheim where I visit quite frequently as a local since I only live 15 minutes away. The WDW's Downtown Disney is much closer to the competition like Universal's Citywalk, which I felt was a much better product.
DD's other problems include the closure of its nightime entertainment. I am sure this will be remedied in the future.
While cars have lost their social status enabling function, buses did not lose their stigma. This is why "nobody likes buses". Buses are alright and quite liked in Europe where the stigma does not exis.
Not that this is an excuse to make people drive substancial distances with buses when one could have just built things closer together. In addition, one would think a theme park dreamworld is the last place to rely on buses instead of cool less economical methods.
Again: True story.