You know when I first went over in 1995, I shipped my bike over without using any "motorcycle shipper". I did all the paperwork, customs clearing, etc. Did I have any problems? Absolutely none. That won't come into play because I usually just recommend renting.
Did I have my first nights accomodation, or any other night booked? No, and never have I booked any in my thirteen years so far...haven't had to sleep in a ditch either.
You mentioned advantages; there are as many if not more, going self-guided. After all, who hauls your luggage into your room while touring stateside?
I once had someone tell me that I couldn't have found the roads he was taken on without a guide. He described the road but didn't know where it was exactly (what happens when you go on an organized tour). I did take it and even have a video of it. Sent him pics. Never heard from him. Guess he was pissed.
By the way, roads are numbered, even the side roads...242, SS46, etc. and they are on the map.
Suggested routes? Trust me, touring companies don't have a patent on those. I have a link to a site where you can download them for FREE. Those maps of suggested motorcycle tours are put out by the ADAC; the German auto club. The link to those free maps is in my second post in the link under my sig pic.
So if people suffer anxiety attacks, are unsure of simple navigation, are uncomfortable with foreign languages, and on and on, then by all means fill your boots and empty your wallets...go organized.