I mean why not just tow one of those trailer thingy's ?

For the same reasons some people have trailers for the bikes.
My brother has 3 bikes, 2 Sporty's and an older EG with a sidecar. He has a severely handicapped son who's greatest pleasure is going for rides.
Because of his physical condition and and the amount of "stuff" he requires, a sidecar was the only way to enjoy biking with him.
My brother has envied the 05 red SEEG before I even got mine but financially is way out the question. Those without handicapped children have no idea on the strain it puts on families.
But, there is no doubt, if I hit a windfall tomorrow, I would find a 05 SEEG, red of course, and have a sidecar installed and painted in SEEG colors for my brother. And of course a couple of CVOharley mods for good measure.