How would you like to troll around the lake and see brush piles, stumps, ponds etc out to either side of your boat? It isnt a necessity but it is a useful tool. It doesnt guarantee you'll catch anything but can help you break down areas of high probability to fish. You probably already use a map, they will give you a built in map that will tell you exactly where you are or allow you to mark a safe trail to follow.
I dont think that it takes the sport out any more than tackle upgrades have done in the last 20 years. It really is a personal preference