Simply put, no one really cares about the logo anymore. Today, people are more interested in what a brand can do for them. Great brands are discovering that logos or advertisements are losing relevance, and instead put their efforts into creating social brand platforms that invite participation and create value in authentic and relevant ways. The real reason the Gap logo failed was that it wasn't backed by any of this; the same goes for Tropicana and the rest.
Logos create value for brands, but social brand platforms create value for people. Nike+ helps people run and get healthy. Facebook keeps people in touch with friends and family. Etsy connects cottage industry craftsmen with buyers. Converse has just announced that it's building a recording studio in Brooklyn to help up-and-coming musicians.
Social brand platforms are not experiential marketing gimmicks. They do not exist to promote something else, but rather they are useful in and of themselves. A logo, by contrast, doesn't actually do anything.