"I think the tone of the show has certainly changed over the years, because it's really, really hard to do something different when you have a show going on as long as this has"

Dan Castellaneta's quote talks to the difficulty of keeping a program fresh and interesting over a long period of time. He acknowledges that the tone of the show has altered throughout the years, likely due to the need to keep audiences engaged and entertained. This is a testimony to the show's authors and manufacturers, who have managed to keep the show interesting and appropriate in spite of its durability. It also speaks to the show's capability to adapt to altering times and trends, in addition to its determination to take risks and try new things. The quote likewise implies that the show has actually achieved success in doing so, as it has actually been able to remain popular and effective for such a long period of time.