Aspergers or ADD cause the same amount of harm and impairment as someone who enjoys sweets or is lazy. Should we give people chemicals for lazyness now? It's a personality trait, nothing more.
No they don't. They don't even compare. That's incredible ignorance. If you're so sure try giving yourself ADHD - brain injury in later life will do it - weak short-term memory, emotional dysregulation, unreliable impulse inhibition, most and occasionally all of it. Statistically, you'll probably find yourself having more accidents, including serious accidents, more episodes of depression and anxiety disorders and from an earlier age, and an 80% chance of developing insomnia by middle age. Incidentally you'll also find yourself more likely to be overweight and have trouble losing weight because ADHD is one of the many problems that people self-medicate with food.
Whereas eating too much, while often contributed to by mental conditions including ADHD, in and of itself is not a problem with anywhere near the hideously long list of long-term correlations untreated ADHD has. It's possible to be lazy and eat too much while functioning as just well as you want to and enjoying life unimpaired by it. When these habits do become so extreme they significantly affect quality of life then yes of course they should be reversed if possible, and sometimes that's helped by treating underlying psychological problems leading to self-destructive behaviours. Obese people with ADHD have been found to lose weight much more successfully when their ADHD is treated, just as obese people do when any other contributing mental condition such as major depression is treated.
Exposure to cigarette smoke or alcohol in the womb, premature birth (even very mildly premature), small size at birth, higher than average lead or mercury levels (not often even high enough to be officially classed as poisoning yet but higher than is found in non-ADHDers none-the-less) all these things are among the most common contributing factors in ADHD, along with genetic neurological, metabolic and immune differences.
These and many rarer environmental contributing factors are all recognised as being bad for someone's long-term health in other ways, and there is no doubt that they frequently cause subtle-to-moderate damage to the brain, which happens to be smaller in all the main areas in ADHD patients regardless of IQ. When an impairing personality trait is associated with things that are known to damage the brain, and with a smaller brain especially in areas most vulnerable to perinatal complications, I don't see how you can possibly argue that it's not a condition that needs treating.