For trail riding they are good.
I never though they would be useful(other than high hp/spinning wheels inside tires), until 2 times I have had a stick jam between the wheel and tire on the front, both causing a substantial leak, and one requiring the bead popped off the wheel and reseated to fix.
I will be buying a set for my 700 when the stock tires wear out.
Do you Need them? No.
But they can earn their keep real quick too.