I'm with you regarding credit cards, and here in Europe few people have them. I usually use cash in my everyday life, but then if you do travel a lot, a credit card is the way to go.
Many cruise lines ask for a deposit from passengers who would like to settle their onboard account using cash or traveler's checks (a good alternative to cash as stolen traveler's checks will be replaced) and a credit card is much more convenient. I really don't like to carry large amounts of cash around in surroundings I am not familiar with (e.g. getting to the ship).
So, while I do agree with you that in everyday life you can get along very well without a credit card, you might want to consider getting one for "use on vacation".
Just my humble opinion, though.