I think the issue I have is simpler. My understanding is those that were obese and have lost weight still have a higher chance of getting type 2 diabetes than those that were slim throughout their lives. If your chance of getting diabetes is 70% while obese, and 2.2% (or 15% or whatever it actually is) after losing weight, how is that not a win?

It is indeed a win. It's long been established that for obese individuals even 5% weight loss reduces comorbidity of obesity-related conditions. Of course greater weight loss, 10-15%, gives better outcomes. Typically the difficulty is maintaining lower weight for the long haul. For those who can do it the payoff is substantial.