It's not necessary if you camp a lot and leave water in the system. I would recommend putting it in if you drain your tank when winterizing (storing). It only takes seconds to burn up the element if you turn it on without water in the heater. Yes, I did it once. when getting ready for the new season, I flipped the switch and a moment later realized I had not flipped the bypass valves to fill the tank. Turned it off, but the damage was done. Grrrr. Now I put it in and it acts as a reminder to check before I turn it on. Use the needle nose as suggested. It makes it a lot easier.
Bob and Joy
2013 Sunseeker 3010DS