While the latter effect is nice, the main reason to be playing Archetype of Aggression is the former effect
Sometimes opponents will try something absurd, and you have to be the voice of reason at the table (or risk losing to a wild play)
(It cant be blocked except by two or more creatures.) Choose a Background (You can have a Background as a second commander.) 2/2 Illustrated by Wayne Reynolds Standard Not Legal Alchemy Not Legal Pioneer Not Legal Historic Banned Modern Not Legal Brawl Legal Legacy Legal Comp
You can just sit back with one of the countless cards that let you add a counter each turn like Innkeepers Talent and grow your whole board for free with Wakkas second ability
So you know you are only going to have them for a very limited time
There is a legal phrase called promissory estoppel, which essentially means that if your promise has serious repercussions for the other party and by not keeping it you caused some sort of harm (financial, in this casespoiler alert), youre liable for that harm and can be prosecuted