I don't get the distinction you're making. I'm not an expert in mobile messaging so maybe I am missing something obvious.
And what about WhatsApp?
My iMessages are for conversations with people that I actually want to talk to. The notifications are high priority because it’s with people that I want to talk to.
I can’t imagine my annoyance if I were to receive an iMessage notification while I’m expecting an important message, only to find that it’s more spam.
My email inbox is already a wasteland because of this. The absolute last thing I need or want is for the same thing to happen to iMessage.