If your bike is 100% stock sure why not. But if you've rejetted or done other mods I think Kawasaki would cite those mods as voiding the warranty.

 

Don't get me wrong, there is a time and place for extended warranties. I've bought some and used them too. I also tossed it around a lot when Kawi kept sending me the paperwork. I decided against it and put my money towards a new slip on, air filter, and DJ kit. At that point I figured an ext. warranty would be voided anyways.
These bikes seem to be very tough and pretty reliable. Not to say that all of them are going to be rock solid, but I bet a majority of them are. If you're going to keep the bike in it's stock form, put tons of miles on it, and need some piece of mind, it's probably worth it. Will the warranty come into play? Only time will tell.

 

Waste of good cash. These low reving engines last forever as long as you check valve clearances as per service manual and keep clean oil and filters.