The kids no doubt are missing daddy because there was no one like him. He interacted differently with them than their family and grandma do. Even though these people love them. Daddy hugged them differently, loved them differently, talked to them differently. They had their own home with daddy. They went out to exciting places with daddy. Everything is now different. Who can they talk to if they have a serious issue about their experiences and feelings in this new life--Latoya (God help us), grandma (too busy and elderly), the uncles (too busy looking for money schemes), the other aunts (too busy or selling MJ stuff)? They know they are loved, but to me they miss something that only daddy could give them.
That's why it makes me upset when people imply that the kids are happier or better now that Michael is gone. It is not said directly but implied with comments that people even in his own family make in interviews. I hope the kids will have healthy and happy lives. Michael would want that for his kids. But he gave them a father's love that will never be replaced. He was their world and they were his world.