I think the answer varies from owner to owner. Here is my thought: is it worth three dollars every day of the year for the peace of mind that the extended warranty would bring to you? That is ninety bucks a month. Every month.
If the answer is "yes" then it might be a good idea.
Also, I think it depends on how well a person maintains their rv, how old it is, how they use it, how they store it and perhaps most importantly are they capable of doing many or most repairs themselves.
It just seems to me that what is appropriate for one of us may or may not be an important consideration for others.
For example, I keep a very high deductible on all my insurance for vehicles and our home. I have driven over a million accident free miles over the last many years and haven't had a claim on our house in two decades. SO, I saved a bunch of money with the lower premiums. Essentially, I am self insuring for a large amount. That works for us, but many would simply not be comfortable with that approach.
On our motorhomes over the last thirty years, I really enjoy doing virtually all the maintenance and repairs myself. It is a part of the hobby for me. To many, that would not be the case.
I think you just need to decide your comfort level and personal situation. Hope this helps.
Paul