For me, since I often camp on my own with out my husband, I needed something that I could manage on my own. I don't have the trailer hitch on the back of the trailer, so I couldn't put a rack there. I drive an SUV and trying to get bikes off the roof would be hard for me (I am not a tall person, and I have fears of doing more damage to things by trying). I have considered the rack that goes between the truck and the bike, but there are advantages and disadvantages there. I do take my bike camping, on boat trips, and around town with me. It is what works for me.
Different strokes, for different folks. I have been very happy with it.