My two cents is I believe that adding more forums is a bad idea.
To continue the reasoning, why not a separate forum just for technical discussions? A separate forum just for parachains? A separate forum just for governance meta-discussions?
We already have too much information spread out everywhere. Even though I’ve been working on Polkadot for 6 years, I barely know half of what is done and what exists, because information is impossible to discover. I don’t know what I don’t know, and since information is spread out I can’t even discover what I don’t know.
The fact there is a single forum for everything is a huge plus.
If you create a forum specifically for Kusama, I am absolutely sure that I will never read any of it. If you post Kusama-specific topics on this forum, I will read all of them even when it doesn’t concern me.
Decentralization just for the sake of decentralization is in my opinion no different than cargo culting.