I don't mind the 30 min wait either. Granted, I get super antsy when I *really* want to see that new baby pop out, but its not life or death. LOL However, I would agree that it'd be great if they would just stay put for a bit, because I sometimes need to leave the sim to take care of other things and come back to find my new baby has gone off to play before I have even said Hello.
Its not that big of a deal for me since I have the HUD and can easily retrieve said kitten, but I do understand the frustration.
I think the 30 min wait is a small price to pay for so many of the other features we have. I believe there are other breedables with a similar wait time as well. It just means we need to plan ahead a bit and schedule knowing its going to take a full 30 mins for that baby to birth.