I don't necessarily see why Jack would've shared his last wishes with Ennis. Come on, they were in their '30s @ their last meeting. They probably assumed that they would live to a ripe, old age. Death was not imminent, so there was probably no good reason to address last wishes. Now if Jack and Ennis had been in their '60s, ...
Even though I'm younger than Ennis and Jack upon their last encounter, I've never discussed my last wishes with family and friends. It just doesn't come up. I suppose I should take that as a sign that I should "put something in writing," because I may not live to a ripe, old age, eh?
Because he was a husband and father, it makes perfect sense why Jack discussed his last wishes with his wife. They also had a family business. Their financial adviser or CPA likely recommended that Jack and Lureen make provisions for son Bobby in case of the unexpected death of one parent or both.