I think that it's great for those with the patience and financial resources to wait until they can buy something outright with cash. However, I'm not willing to wait until I have the cash to do so. I use my very good credit responsibly because I want to have an RV to enjoy now - not later.
You see, unlike time, money is something you can earn more of. Time, on the other hand, is finite (from my perspective/life); its passage is unceasing and therefore not something I'm willing to squander. I've got a limited amount of it and I choose to use some of it in my RV ... not waiting to buy one.
My two cents - paid in cash. :)