Q: When my grandmother died, they decided to hold a huge lunch at a restaurant. Same thing when a cousin died. I heard that this is common for JW. Why?
A: Because it makes sense and is considerate. Some people have come from afar. Some are in no shape to cook. I don't think it is unique to Witnesses. I think it is more common than otherwise.
In cases of family, I remember in my youth people lamenting that the only time the whole family got together was for funerals., as though love itself would not suffice, but only an obligation. I finally decided to run with it. It is what it is. Death in this system of things is a natural course of life. Use it as a metronome, to reliably bring everyone together from time to time.
Kill two birds with one stone. Bring everyone together and use the power of family to help the bereaved one heal. Stay the course, and the time will come when there is no death.