I don’t use What’s App for the simple reason I like how my contacts are integrated across my Apple devices. From email, to “normal” phone calls, to Siri, calendar invites, and even directions “hey Siri, directions to Tom’s work” — it all works seamlessly. If I want to send someone a location from Maps, it’s seamless. If I am using something like Find My, I can easily send a message from there — or even create a Shortcut to send a geofenced message. And Memojis are just simply fun. When I am on the road, sending my kids a message with a talking robot really makes their day.
I also have big trust problems with Facebook products. Apple makes iMessage to sell devices, what does Facebook do with What’s App? There have been reports in the past that installed Facebook, Inc., apps were sending analytics from devices on other apps people were using, pretty much like a Trojan horse. I don’t want any installed Facebook related apps on my devices because Facebook lost my trust long ago. While supposedly What’s App is “secure,” the entire history of Facebook has been littered with “oops, you caught us and we are really really sorry this time.”