I don't see why they haven't just integrated whatsapp into Facebook itself and allow cross posting, that does away with the need for them to have the two similar apps. I also don't like being forced to allow two apps on my phone if I want to send messages to family members anyways, I feel like it was mostly a grab for more data to sell than a necessary separation.

I've seen a fair chunk of resistance from family members when it came to installing Messenger on their devices. Personally I think its good as I can still keep in touch with people (while having removed them as a Friend on Facebook) without the need of having that via Facebook app installed on my phone. It's hard to get everyone onto the new/best messaging service, but almost everyone has Facebook.