I always used to think Whatsapp is designed so well and there is not a single thing that can be changed about it, I must tell you, you have done a pretty good job in dissecting it. In retrospection now, I realized I have come across some of these problems. However, all the solutions proposed by you may not be feasible due procedural knowledge. Further, when we want to ignore the chat we don’t open it, I wouldn’t enter the chat that I don’t intend to reply and once the chat is sent to “Ignored” I believe it will stay there till the end of end of time.