Its promotional card status, energy cards attached, and brilliant design earn it an essential spot in the card games, having, in the past, dealt opponents powerful blows in competitive matches
Although I put it on 3 in my personal list for Modern , this specific decision was definitely harder than for the rest and I can see how in a vacuum Expressive Iteration can be the true winner
Varchild, Betrayer of Kjeldor could be fun in some sort of group slug deck where you give your opponent tokens but in a harmful manner (maybe with something like Trespasser's Curse on the battlefield), although she might be better in the 99, since mono-red is pretty limiting
We can't afford to run out of tokens, so somehow we have to keep them safe
Having two commanders allows player to be very flexible when constructing their decks, as they can mix and match strategies to optimize their build