Are there not still populations that have high carb diets and have very long lifespans and generally good lifelong health as well?
That still doesn't make carbs good. It just means they have long lifespans in spite of eating carbs. There's no redeeming qualities in carbs compared to proteins or fats.
Also, it should be pointed out that a lot of Asians have pre-diabetes or diabetes....they just don't know it. So the fact that some cultures lead "long lifespans despite eating carbs" is misleading. They are living long lifespans DESPITE eating carbs.
Edit: added some stuff from h1nch and The Shadow from below, thanks.