It is useless because none of the people I need to talk to use iMessage, and they have iPhone. They are all in LINE. Others have Samsung, so you end up using LINE anyway, then everyone eventually ends up using LINE.
So they never use the Messages app on the iPhone. Because iMessage is built in and would work if they used the standard app.
But if they want to use a third party app? That's fine. I'm sure LINK has compelling features that can't be done on texting or iMessage.
But that doesn't make iMessage a less compelling feature for iPhone users.