It's the only chance for obese people to lose weight in a healthy way, in a acceptable amount of time. When you have a lot of unsuccessful attempts behind you, your body is already fighting anything that you might try to get rid of your fat, and this body has experience of hundertthousands of years. Starvation, which is part of all diets, is for your body nothing else than a signal to cut energy costs down to a limit you wouldn't even dream of. Cooling down your body temperature, degradation of your muscles and decomposition of your bone structure, together with reduced metabolism and cutting down organ functions.
What I think comes a bit short in the discussion in media and the medical world, is the negative side of the surgery. Every voodoo has its costs. Not only the calories bypass, the necessary vitamins, minerals and proteins do as well. In the end you replace the drugs (which the obese people need for compensating blood sugar issues, cholesterol, heart problems, apnoe etc...) with vitamin pills, mineral granulate and protein shakes, which is better than health issues, but a real boost to life quality is something different.
And then there is the problem, which surgery can't resolve - the energy expenditure. After a decade or so most people gain weight again, the body's austerity policy finally wins and the patients need another surgery. So it's certainly part of a solution, but there is so much more to be done than swinging the scalpel.