To say that you have to go out west into the mountains to ride a full suspension mountain bike is actually quite ignorant. I rode Fruita, Kokopelli, and Moab, and found the terrain to be much more forgiving than the stuff I usually ride in Copper Harbor. BIG technical is full of nice, smooth sections of trail. The difficulty comes with the amazing freeriding terrain that is offered out west. Small and tight technical, like what you find on a lot of Michigan trails, is exactly what full suspension bikes are designed for.
I find that 4" of travel is a very nice bike to have for downstate trails such as Highland and Pontiac Lake. It's not necessary, but what is necessary is dictated by the needs of a particular rider, not by what others think. In Copper Harbor, larger travel bikes are much more popular - upwards of 6" of travel. Our trails are built on bedrock and we have some massive root systems. We also have some fun drops. We also like to design some trails for those larger travel bikes. It's just a different style of riding and it can be a lot more fun in the sense that it will allow some people to push themselves farther than they otherwise would.
A view of Brockway Mountain beyond Lake *beep* Hooe, and Copper Harbor from the East Ridge. This is where we ride. Brockway Mountain is 726 feet above lake Superior, and 1,328 feet above sea level. Yes, we now have a Brockway Trail that climbs Brockway. Fun stuff.