I understand where you are comming from. I think part of it is that Starbucks is so prevalent and commerical that it can seem to be a bit of a shock. However WDW has a long history of having a variety of corporate sponsors in the parks, both large and small. Form Orange Bird, to the aforementioned Edy's (Not Ed's, not Edd's, and not Eddy's) which is the same as Dryers out West, and is actualy a Nestle company - about as commerical as it gets. McDonalds had fry places all over the place, Kodak photo spots abound, let's not forget the huge Seimens logo on SSE every night as you leave EPCOT. I could go on and on with corporate sponsors that are in WDW.
I for one have no love for Starbucks (I don't like liquid coffee flavored candy, and their normal coffee drinks - espresso, Americano, etc are pretty bad. Ther food is usually fairly dried out as well. But their blond roast is passable). So from that standoint, I was not thrilled to see them in the parks (although their coffee is a step up from the bag in box coffee concentrate (made by our good friends at Nestle again) that WDW used to serve. I would have liked to see the Main Street Bakery stay, just from the standpoint of food quality.
Starbucks is a bit of a trigger for many people - not just in WDW. The town I live in is dead set against Starbucks. They do not want one in town, because it will increase the commerical aspect of this town and will draw in traffic from the highways. But they are all for an independent coffee shop. Because you can't swing a dead cat without hitting a Starbucks, it serves as an example of corporate homoginization and unification. That is the reason many people have a problem with it being in WDW.
-dave