The old is sometimes the best
This is an attack against the crass consumerism of our age and how the good, faithful, and familiar are at times better than the wonderful new item that is blasted by advertising logos that are constantly splattered across our vision. The story is about how a young bear, wearing his favourite hat, is wondering through the city and sees a beautiful new hat in the window of a hat store and decides that he wants to get rid of his old tatty hat in favour of something fancy and new.
However, as our little bear begins to explore the cornucopia of hats that make up this hat store, he discovers that each and every hat that is shown to him is just too gaudy, too colourful, or simply too silly (though at no point in the book do we discover that a hat is too expensive, or whether the young bear actually has the money to purchase a new hat, or has to whip out his visa or mastercard and pay for it on credit).
After going through all of the hats that are available in this hat store the young bear suddenly spies a hat that he finds to be perfect. Much to the disgust and disappointment of the store owner, the perfect hat is the faithful old tatty hat that he walked in with, and we can even see the anger and disgust on the store owner's face as the little bear models himself in front of the mirror and then walks out of the store the proud owner of his old hat (for which he did not have to pay a cent).