Well of course! I'm not some dumbass, okay? Of course they are "important", but they already exist on the system. They are already installed. Like every other update, it is an update. Now please, this is starting to get rather personal, and it is kind of a matter of taste. If one choses to format just because one thinks it's fun, then sure... Fine by me. I'm just saying it's not vitaly important to do so if you want to update your chipset drivers.
In most cased where you would chose not to format first, you will not have any problems because that was your choise, and most of the cases where you DO have a problem, it is probably derived from updating at all. Then of course, there is indeed that very very small chance of screwing things up by not formating first, but let's be honest. It's smaller than the risk of being killed in a plane crash! (which most of you probably know is VERY small)
I for one, would not go through the trouble of formating, if I wouldn't need it because of something else.