I'm pretty sure that the minor glycemic spikes after sweeteners (artificial, zero calorie) is because they're sweet it's a combination of some glucose mobilization and insulin response that shapes the results after use of artificial sweeteners. You're carrying a fair amount of glucose in the kidneys which is quickly available and glycogen the muscles that can be activated nearly as quickly. The impact from this on those that consume a lot of sweetened beverages over the course of a day may not be such a good thing and may even contribute to insulin resistance.

Aspartame is really inexpensive compared to real sugars... the sugar industry really doesn't like it and that was well before sucralose was an option.

My personal take is it's probably best to limit sweetened drinks to with meals, and to limit meals to 2-3 a day in a relatively narrow window of 6-10 hours.