Science baby made me super excited for the new update. I don't mind lack of pregnancy. It's not my favorite part of sim life anyway and my sims also rarely have kids at all. But I think it's an awesome addition for those who have settings to can't get pregnant/can't get others pregnant. I play with a few trans sims and personally seeing them pregnant would break the immersion for me. It's also a personal choice, because I dislike pregnancy IRL and would never go through this myself (nor would I sentenced my fav sims). For those who are excited to have pregnant characters, there are plenty of options like going into CAS and setting their preferences accordingly.
Science baby is the option for people who want a genetic kid without the experience of big belly for realism or just because they are not thrilled by the whole process. I didn't expect this part of the base game update and I'm happy that developers are thinking about all types of players, including those that physically cannot or simply don't want to be pregnant, but want to have baby genetically connected to parents. Now, please, let's fix the base game/Spa Day nails for trans sims and I will be a happy camper. :)