The Eaton Centers in Toronto and Montréal also come to mind. They're huge, and intimately plugged into the center of the city, including being directly connected to subway stations.
That said, they're also, I suspect, mostly for tourists.
The Milwaukee area's malls really make the situation for suburban malls clear: The city buses do go to the malls, but the malls wouldn't let them drop people off by the door. They stop at an open air bus shelter at the far end of the parking lot.
My first guess would be concern that buses driving all the way up to the mall would somehow impede the flow of traffic for cars.
My second guess would be that, Milwaukee being such a suburban flight city, there are certain. . . perceptions. . . about public transit and the people who use it. I used to end up in some rather uncomfortable conversations when people found out I regularly used public transit.
My best guess would be that it's officially one, and unconsciously both.
Note that those three cities are also quite cold in winter - connected shopping matters when it’s -30 in January. Montreal’s underground city/malls are literal lifesavers, not just shopping. Matters much less in moderate areas.
That said, they're also, I suspect, mostly for tourists.
The Milwaukee area's malls really make the situation for suburban malls clear: The city buses do go to the malls, but the malls wouldn't let them drop people off by the door. They stop at an open air bus shelter at the far end of the parking lot.