I'm lucky enough to be in an area with a ton of local coffee roasters, so I'm never that far from a good cup. But even before coffee became an addiction for me, I didn't like Starbucks coffee. The plain coffee is too burned and doesn't taste good, and the mixed coffee drinks are too sweetened to cover up the burned flavor of the coffee. These days if I can't get to a local coffee place, I'll just go to an AM/PM or 7-11 as they'll have better coffee than Starbucks.
It makes grim sense from a business perspective. All coffee has a unique flavor, but all burned coffee tastes the same. Burning all the coffee ensures a similar flavor profile at any Starbucks in the US. The fact that the flavor is bad is entirely beside the point.