ATT has 117 million subs now. Just because you have been with company 20+ years does not make you special any more than the other 116,999,999 customers.
My parents have been vz wirless customers for 32+ years since ameritech and GTE days. They dont expect anything more than what a new customer gets.
Now on to your problem. You can just buy an unlock code online now. Yeah it will cost you a few bucks but your phone gets unlocked.
You cant blame a company like ATT for having rules on contract phone and next plan phones. You got a huge discount on the phone. Att I have found in the past year since they released the new unlocking rules is very rigid when it comes to unlock codes.