Because people were still hoping for a diplomatic solution while China and the US are playing chicken. The problem is coming to a head now, and the can will no longer be kicked down the road.
You're right, NK is just a pawn, and unless they start acting like it, it will cease to exist. This fact needs to be impressed on KJU if we're to avoid war.
I am sorry that your points are getting confusing to me.
You are saying that "unless US and China act, a war is assured". So the center point is that war.
My question is then, the war between whom and whom? And who is forced/wants (two sides of the same coin) to start that war?
Since China will not initiate a regime change in NK (starting a war with NK), it is only war between NK and SK/US initially. Agreed?
China will only get herself involved in that war when SK/US is going to overrun the whole NK (a little passing 38 may be tolerated in the beginning). China got involved last time in 1950s. And China's involvement is guaranteed to happen this time around too. That is not something China is trying to avoid or afraid of getting into. One does what one have to. It is to say that China does not want a war on the peninsular, but China is going to avoid or afraid of getting into it. When shit hit the fan, so be it.
I feel that you have an assumption of China or preference of avoiding war at all cost? I think on the contrary, that assumption or preference is simply not there in the Chinese mind.
Last, let us remember what Chairman Mao said once in another event but making a good sense in the Korean peninsular issue, "天要下雨,娘要嫁人,随它去吧". You know what that means if you read Chinese.