That's because WS became appreciated for what it is, not what it allegedly attempted to be (tourism promotion)
WS is like Main Street, but on a much larger scale and with far more variety and quantity when it comes to architecture, landscaping, shopping and dining. People appreciate and treat the space as a walkable neighbourhood. A place to meander and explore at your own pace, and to gather eat and view entertainment. It's far more popular than any version of Downtown Disney because it is so much nicer and offers things the latter doesn't (Circle Vision shows, rides, character meet 'n greets), all bundled with admission to the rest of the park.
No other Disney theme park has a comparable experience, that's also as big as other Disney theme parks.