Per the article # 5:
5. Customers who choose to upgrade at the end of their current agreement are required to sign-up for NEXT, bring their own device or purchase a phone a full retail price in order to keep this plan
So if you have a capable device that you can bring over, that is great or if you have the money to buy a phone outright that is great. If you don't have either then the NEXT plan is your only option. I got that from the article, plus when I tried to sign up with AT&T online as a new customer my bill jumped from $130 to $180 because I had to get new phones and would be put on a new contract. I then did an online chat and was told that in order to get the $130 I would have to join the NEXT program. So yes my bill would be $130, but I would have to pay $25+ for the phone rental.
Apparently your experience was different, but from online chat and going through the steps online my quoted price was higher than the $130 that their new pricing shows.