Hmm. Generally I wouldn't like doing that, because it would just be like a really long way to make new townies. However, it's a good idea for excess children I have no intention of playing. I hate sticking them in a house and then seeing that plumbob there reminding me of their exile. Leaving them in the bin is too much like putting them in the naughty chair.
I went ahead and did a boolProp - create all townies on my new neighborhood. I like getting my family sims married off ASAP, especially since money is tight in the beginning. I kind of wish I'd used new default face templates (my game has been in a royal squinched-eye trend and I prefer anime ones). Maybe I'll restart...again! I'm already regretting using the default downtown instead of creating one with some of my own lot creations.
I don't do it to make townies, I don't like townies - they are just a waste of character files IMO.
This way my sims never turn into elders (boring) and they never die (unless they piss me off). I also don't have to watch the family boohoo about them being dead which is a plus.
I start the game with 4-5 families which is enough friends to satisfy the need friends for careers and the game generates other people to make friends with if needed (paperperson, mailman, maybe a delivery person) until the toddlers grow to children to roam the neighborhood unsupervised.
I did create my own dormies so if the teenager don't hookup by that time they can have a selection of dormies to select from.
This style may not suit everyone but for those trying to keep character files at a minimum I wanted to share it.