This is because your old grandfathered plan doesn't give you a discount by using Next. So yes, taking the subsidy is the best choice for people like you. However, Next is not a scam for most of the customers who aren't hanging on to old plans, where they get a discount monthly when using Next which makes them both roughly the same.The point is you have to pay off the remaining months on the phone even if you sell it.
A year into the next program I will have paid around 600 for a 6+ 124 gb. even if I sold it at this point I would be responsible for the remaining payments whereas with 2 yr subsidy I'm paying just around 600 to own the phone outright
It is simple math.
Either way you look at it, you are paying for it. With Next, you can sell it at any time but as long as you make payments for the duration of the loan it's not a problem. With your unlimited plan, the cost of the phone subsidy is built into your plan, so you are paying it even after the phone is paid off.