but the problem is that you make one of these once and then set it on your shelf
Since we're going on anecdotal evidence, this isn't my experience at all. You do still have unthemed sets, and anyway it isn't long before kids mix and match their pieces, breaking old models and making new ones. That's certainly what I did, and what I see my relatives doing.I don't know, what common "toy" do many children have these days that is neither healthy nor active? An iPad/computer!
Well, you kind of missed my point, man. Sure, an iPad may be neither healthy nor active, but what's important is the parenting environment. When I was growing up many of my friends' parents used tv as a babysitter. My parents encouraged me to go outside, read, and cycle. My point was, the presence of technology itself isn't the pretty exaggerated societal harm you make it out to be. It's how parents raise their kids that actually makes a difference.