^^^That may be. My mother has two kids, was raised in Chicago, after grad school ended up in NYC. Then was transferred to Madrid, Caracas, Buenos Aires and finally Miami. Her opinion was to move to Jacksonville, where her husband, my father, was raised (not born). She was strongly against staying in Miami, even though she lived in Coconut Grove, a nice area even in the 80s. My father lived on Brickell. I would say she was pretty experienced, having had me at age 36.
Of course I have cousins raised in much larger cities, and I know their parents wouldn't have had it any other way. Different strokes for different folks. I love living IN large cities' urban areas, but then again I will never have kids or be married.
I do work on 3 condo developments, though, in 3 cities' inner areas (Manhattan, West Midtown Atl, DT Nashville), and I work on multifamily in DC (Georgetown) and Boston (Back Bay). I have seen the resident profile of each. They are each different, but out of the combined 522 units there might be 5 families, I'm not kidding. My own neighborhood's profile in a nutshell is young prof, gay, student, empty nester, very occasional family. Nearly everyone in Midtown Atl lives in multifamily. As soon as you get to predominantly SFR neighborhoods, even ones where the houses don't really have yards, then you start seeing more families.
Of course we are talking Springfield here, not Bed-Stuy or Hoboken or South Loop. "City" is relative in Jax, but personally I would be weary of raising kids in Springfield because I would be concerned with proximity to crime and just the general pace of the gentrification of the neighborhood. You could live in the middle of the tiny so-called "bubble" that is Springfield and if you allow your kids to bike around like most kids do, they only have to go like 3 blocks before they're in real rough areas with high crime. I don't need to already have kids to know that for me personally that would be highly unappealing, but to each their own. I would wait for the gays/artists to sweep through the area a little more, revitalize a much larger area more than it is now, and then I would very well consider it. San Marco is equally close to downtown and just a much better "side of the tracks" for raising kids, in my very personal opinion. But to each their own.