It provides detail, grounds the characters in the setting, punctuates the scene with action -- as long as you remember it. Too much detail is unwise, since the actions are, after all, routine to the POV character. (If they are not, you are in the much more interesting arena of doing two things at once which is harder to pull off.) But with too little, you lose touch with the concreteness and reality of it.
Selection is a particular art, especially when doing something the reader might not be familiar with, like building a fire. How to figure out which details tell and convey enough. . . .
It gets even more interesting when you want the POV character to forget what he's doing in the heat of the moment and only remember after some passage of time with having completely -- or more than completely -- finished what he was doing, or having dreadfully botched it in preoccupation.
