It is absolutely worth it and recommended to replace your battery when it has passed its duration. It will cost you some money on a new product and a possible servicing fee. But trust me; you want this for your laptop. Because it will be more cost-effective than replacing the laptop.
Laptops are such a flexible tool that can be used anywhere at any time, you could bring it with you wherever. This is possible mainly due to the battery giving it prolonged run-time. Without it, you are basically running an inferior desktop in practically every way.
Always running your laptop on a direct power supply may lead to certain issues. First, the power has to be on constantly or you cannot run it. The voltage may fluctuate which may damage your laptop’s internal hardware. Because the consistent on and off will lead to problems inside the circuits.
So yes, you should replace it when the situation calls for it, especially if your someone who uses a laptop on the move. In the meantime, you have to use it properly so that it lasts for a long period.