The medications have been around for 20 years - they aren't new.
They work by switching on/synthetically replacing the hormone receptors for the GLP1 hormone, which is released by the digestive system which tells the brain when its hungry and when its full. These receptors not working effectively also create the "food noise" even when a person is full, their brain doesn't get the message properly, so they think about the next meal, the next snack, constantly.
They still require will power, good choices, and exercise.
They work for people who have a hormonal imbalance that has contributed to weight gain. It clinical trails, some 9% of people didn't respond. That means that 91% of people do, and they are overweight in part, because they have a hormonal problem.
Obesity IS a disease, its scientifically proven, that this genetic, biological hormone imbalance is a large factor in many peoples weight. These people, in a lot of cases have struggled their entire lives with their weight, have yo yo'd, have tried the age old "eat less move more" society has drummed into us, but hat just doesn't work.
A medication to correct the hormonal imbalance allows a person to be successful, and healthier. It needs to be regulated. Paying privately is not an issue as many people are choosing to make the money available. Prescribing on the NHS is only going to save money long term as in the UK its a relatively cheap drug.
Because of how it work, it is designed to be on for life. Its doesn't cure or reverse the hormonal imbalance, it replaces while using, but if new habits and relationship with food is created whilst on it, a person can continue success off it, but using it for life in order to manage a hormonal imbalance is also an option.