I think some of you are making the assumption all trucks have a "bed plug" or holes pre-drilled for one. This is not true.
I use a 6-pin plug when I Flat tow my Samurai. I use a flat plug when I tow my utility trailer. I used the 7-pin to tow my 5th wheel. I wired my TC for the 7-pin. My point is, I have to deal with adapters or add several plugs. I really have no issues with adapters or the 7-pin "Y". I tow my trailers with other vehicles, so without the adapters I would have to re-wire my other vehicles.
I might be more concerned if I used my truck to charge my TC battery, but I do not. If I did, I would use a dedicated cable with a much larger wire size. I would put the cable connector in the front of the TC near my battery location. For those of you that are not aware, all TCs do not have the batteries in the front.
I am kinda scratching my head at comments that suggest there is only one acceptable method for everyone. I think each individual can decide for themselves which they prefer. Personally, my preferences is to have flexibility and options.
Wayne