I thought the same thing. In fact, I tried annealing the original washers to avoid having to buy new ones for $7 pp. I don't know if the washers I got with the car are truly original or Ebay specials but either way it didn't work.
I've not been using any washer for the oil drain plug but surprisingly haven't had any leaks there. For good measure I'd be interested in trying the nylon ones on the drain plug. Can you recommend a good source or do you figure it doesn't really matter?