They're not trying to reduce the number of hotbar buttons. They're trying to reduce the APM. They want to reduce the amount of actions you cram into every 2-min burst window. They'll probably lower kenki generation too, or make Shinten cost more, so Kaiten doesn't just get replaced with more Shinten spam.

Unfortunately, none of your suggestions are relevant to what SQEX is trying to do. But I agree, Shoha 2 should have just been an upgrade, like Expaciation on PLD.