Several probable reasons -
- Lower attendance due to change in facility. The new one is a change and arguably the transition has deterred some people. Its in a more crowded area; driving and parking anywhere near Fishermans Wharf on a weekend is hopeless.
Fishermans wharf-driven walk in business is not likely to be as strong as expected, as that tourist crowd has few kids.
- The current location is less attractive, smaller, has less stuff than the original.
- Kids attraction in a place thats losing kids - very likely reason. A lot of visitors would be out of towners, but these days I suspect the population of kids in fairly well to do families in the whole area, not just SF proper, is on the decline.
- Did the transition over the summer losing a lot of the summer camp business.
I think your first reason is most likely. Most kids would be coming from the surrounding Bay Area, and that means families driving into the city. As you said, SF is very car unfriendly.
I think it is a combination of all the reasons you list...
few families with young children in SF in general, families that can afford to pay the admission, parking (or transit fare) just don’t see it as worth the hassle (at least not on a regular basis). Schools in the nicer (suburban) areas have expanding enrollment (and not from illegals where homes cost >$1M). The target audience is tech-savvy parents that can afford to spend a bit. But those parents are quite hassled by a trip to the Exploratorium... why bother with so many other good options much closer. The choice becomes the Exploratorium, or say... the Hiller Aviation Museum and an afternoon at the beach (with a fraction of the hassle and for less $).
“Several probable reasons...”
Remember, they are competing with the Tech Museum, as well. Kids in the East Bay and South Bay go there. Lots of fun.