There’s two buttons on SMS notification: Answer (which do the same as notification tapping) and Call. I propose to add third - Mark as read. When messages are short and user don’t want to reply at the moment, this button will delete unread message icon from notification screen.
Second thing is Quick Answer directly from notification. For short answers is not needed to open and switch to Messages app. For example: when watching video or using web browser answer for SMS interrupt this and user must swipe to recall app.