If your writing that long of a message and you miss the send button, IT'S YOUR FAULT!!!! Cause the longer the message, the harder it is to miss the send button.
What's so hard at not touching the screen between the quick reply and the keyboard? Yes, if you're fumbling with your iPhone while doing other stuff, it's possible. But if it's that important or that much of an annoyance, then just FOCUS on the reply which takes less than a minute. Otherwise, IT'S YOUR FAULT!!!
This is not a big deal. I care either way if Apple does something about it or not.