Why do I need to install game updates?

I really don’t now. For what it doing?

Game updates are mostly used to fix bugs but they can also add new features. For example the latest 1.3.0 update for Pokemon Sword and Shield added a few Pokemon (like Galarian Articuno/Zapdos/Moltres) that were previously unavailable and it also made the Crown Tundra available for those who purchased the expansion.