Not all extended warranties are a waste of money, but RV warranties have so many loopholes for them to deny claims that they, in many cases, can amount to a waste of money. My current rig is 7 years old and I wouldn't pay for an extended warranty at this point, plus I'm pretty handy and prefer to do any repairs if I'm capable. Was offered one when we purchased new rig which I immediately denied, turned out to be the right thing to do as we have had no issues that didn't cost a few buck for me to fix myself.
Nothing wrong with getting an extended warranty and some do get costly repairs that can exceed what they paid for their warranty, peace of mind is the major reason we get them and that feeling can go a long way to making the RVing experience less troublesome. Boils down to your personal situation and point of view, I would be more inclined to get a warranty on motorized RV, for towables I would just take my chances and go without.