Spider-girl showed him as a decent dad, but one that was overly strict and over protective, which I thought fit the character well.

Both MJ and Peter would be incredibly hesitant about having kids. Purely because of the lifestyle Peter leads. If a pregnancy does happen, I could see it being a unexpected one. MJ wrestling with whether to tell Peter on not. Some great drama could come out of such a situation. But, again, once you head down that road it is a hard one to backtrack on if editorial or writers wish to ditch it later.

Nobody would want another miscarriage situation to occur again. Nor would they welcome a termination.
That just leaves the only option being to send the kid into the future, and if they do that, you just know he's going to come back as a cyborg with lots of guns.