Actually, they do need to be replaced, if for no other reason, when they become big enough that they throw off the forced perspective and ruin the show. And they have been replaced quite regularly. The big thing lately is the Hub, which had to be adjusted to fit the new show, not the fireworks, but the castle projection show. People like it , people want to see it and the very reason for WDW to even exist is to entertain and make people happy. The few tree huggers that are appalled that Disney would remove a tree also must remember that before they built the place it was a swamp with hardly any trees at all, at least where the castle is located. It's just another example of people that are just not able to adapt to changes that disrupt their memories of their childhood as distorted as that might be.
