It buffs your team, especially with cards like Escape Tunnel and Whispersilk Cloak to let it keep attacking, and cheap commanders are valuable
For example, the Red Cheeks version of the Base Set Pikachu is a Common card, but since reprints turned him into Yellow Cheeks, this drove scarcity along with collector interest
Ramunap Excavator too, I guess
However, one key thing to note about many of the Illustration Rare cards that suddenly explode in price is that their TCGplayer market price can be manipulated if many copies are purchased by an organized group
Some were meant to be public, sure, but others
The graphic they added to the Mystery Booster packs had a square background, and the one they used for The List seems to have a rounded background, which creates a telltale difference in the shape of the cards border as you can see on Chatter of the Squirrel and Ancient Den as well as subtle changes in its placement on new border cards, as seen on Boros Challenger