Common sense is seldom a common virtue, especially today.... ...that's why I think you see the O.M. in a not so direct way expressing a figure saying "if you have the Tow Prep Package you may tow more than 3500 lbs" or 5000 lbs in later years...2014+ 5.7/3.0 get a 5,000 pound rating. I'd want brakes. Also if the axle is equipped with brakes regardless of load you need to have the brake controller wired and working. The trailer can be rated for 7,000 pounds but you can limit yourself to 3,000....again I stress, towing is common sense based.
Yes, I would want brakes for some loads as well..... ....I'm only pointing out, although its nice you get a brake controller pig tail with the factory Tow Prep Package, you shouldn't expect to get one with the Mopar Accessories, it's up to you to get a brake controller and install it, with a pig tail or not....
I don't know if every WK2 has the connector for the Pig Tail. It's possible the connector is there standard, so if you don't have the tow wire harness from the factory and add it with the Mopar Accessory kit, it might connect to the Connector for the pig tail to the brake controller; but that is a pure guess, and the individual would have to confirm this for themselves....