Yeah, 12 life stages is far too many. There really isn't that much difference between most of them. I mean, lap baby to baby? Adult to middle-aged? Elderly to Elder? They're basically the same thing.
I'm not as obsessed with pre-teens as some are. I don't see what makes them different to children. People say "oh they can get crushes..." that's it?? Not enough to warrant a whole new lifestage IMO. Most people talk about them going to "middle school", which is only really unique to American players. This game is very American-focused as it is, most of the new worlds are based on somewhere in America for example. I know there are a lot of American players, but there are millions round the world too. It'd be nice if there was more diversity!
The life stages we have now have noticeable differences between them and each has unique gameplay.