Here's where you're going wrong. In any comparison, you cannot simply remove part of the equation to suit your outcome. Here, the "inexchangable unique kid" part is an integral part of the problem. You simply cannot compare a game that gets old after 3 months of playing to something that'll last a lifetime, with all responsibilities etc.
Yes you can
Say we have a graph of the utility & pleasure of a game and baby from the moment of deciding to have one to when the kid leaves home at 18 and the life of a game from the release date being announced (or beta or whatever) and the point at which you complete it. We simply scale if needed and I guess, in mathematical terms, integrate between limits to find the utility of a certain period.
Toht stated this period in his first post: "A waits for a kid for 2 years. Tries and tries, no go, and finally that one day they find out that she's pregnant." & "He hears that in two years, "Megakill 3000 - Extra kill!" is coming out. He waits and waits, speculates, writes on forums, draws fan arts, and finally that day comes and he gets the game."
Now his explaination is a bit sloppy above but anyone can see that our range is 2 years.
Why can't we cut off the rest of our utility graph and just focus on that bit? In fact - we can.