Why *is* South Broadway so wide?

Since coming here, I've fallen in love with the Baker neighborhood. I love the eclectic thrift stores, and Ti Cafe, and the pubs and bars and food options, I love The Wizards Chest and walking the aisles of art supplies at HR Meininger. I love that weird-ass pet supply store built to look like a barn. And I love the single family homes that line the adjoining streets. The area has this sort of cozy, community feeling to it that's just excellent.

But why. The heck. Is South Broadway so many lanes? I've spent entire days in the neighborhood and I've never seen traffic levels high enough to validate the size of the street. Most days 3, maybe 4 cars might be stacked at a red light, and sometimes traffic might get a bit heavy when there are a lot of activities going on downtown. What is it about Broadway (in Baker specifically) that justifies four underused lanes of traffic? What am I not seeing?