It makes sense once we just break it down...
I know you are being good-naturedly sarcastic, but what you say about breaking it down is correct. :) God already has very specific plans for ALL of us. Even though James and Jude became great Church leaders after the Resurrection, it just wasn't God's plan that they be in charge of Mary's welfare.
Now, who was the ONLY Apostle who wasn't martyred by execution, thus living the longest life? What a coincidence, it was John. Mary could have easily been alive and in need after all of the others were gone. It really does make sense once we break it down. :)