Starbucks svp of marketing, Terry Davenport, explains the companies decision:
Obviously with a brand with such a huge profile as Starbucks, we approach this change very sensitively. We actually explored a very wide range of options, and when we stood back and looked from afar as well as looked close, we all unanimously gravitated toward the images that freed the siren from the word mark. We really took inspiration from companies like Nike where at one point they separated the word 'Nike' from the swoosh in their logo. This allows us to bring our identity to life anytime and anywhere.
Starbucks' logo timeline: