It is based on simple evolution, only in a business sense. It happens to most companies. They make an awesome product, get well known for it and hit a pinnacle. Around that pinnacle it becomes more difficult to increase profits by increasing customer base. So the next thing to do is to either come up with new products or cheapen the ones you have. To develop new products takes foresight with imagination, this can be very expensive and time consuming. Cheapening your product is much easier but can come at the cost of losing customers who love your product because they were loyal because of the quality of your product.
It has taken Disney a much longer time to do this than it takes most companies.
This is a very large overview, there is much more to it but overall I think it has been slowly happening since the around 2000.
