>>95883200 (OP)In and of himself, Archaon has a dumb motive, but he's not any worse off than any other generic Chaos Champion. He could frankly be replaced with someone like Wulfrik or Bel'Akor, or a dimensionally displaced Abbadon, or even Harry the Hammer and they'd serve the same narrative purpose.
Namely, being a tool to make the setting work in Gee Dubs' favor for marketing, aka using Chaos to basically flip the table on things, whether it's giving the Chaos gods the win to end Warhammer Fantasy to get Age of Sigmar, or blowing up Cadia to make the warp bigger to sell more Primaris and Chaos Marine and Primarch models, or the Skaven crashing Vermindoom into everywhere to reset the rules, or whatever else they plan to do in the future. Cause GW is uncreative when they need to change something, they just justify it with "Chaos shits all over everything, now keep buying our merch you paypigs".
But yeah, I don't hate Archaon personally. I just think it's funny to shit on him, since otherwise he's just an edgy asshole in a long line of them who happened to be given the plot armor handjob for Gee Dubs to kill Warhammer Fantasy.