Yeah, I used to be right there with you. Now it doesn't seem that big a deal. The commas in a list are supposed to take the place of "and": Two all-beef patties, special sauce, lettuce, cheese, pickles and onions on a sesame seed bun would look too clunky with all those "ands" instead of commas.

But the last one in the list actually GETS an "and" in front of it! So the comma seems to have a hard time justifying itself at times now. But I know all the arguments for it, used to make them forcefully with great examples, and just used the Oxford comma right there, purely out of habit.