Saw Zella Rose riding in one of these today. It looked super cool, and they said it's actually very stable, despite my first subliminal impressions ("...merciful Jesus, is that a child on the handlebars? Honey, find a cop.")
To use this device (which is probably safer after all than the rear-mounted kind, since it's right in the middle of the center of gravity, rather than way out back), you'd have to be mentally prepared for some public finger-wagging, tsk-tsking. But then again -- that's what we gear up for whenever we leave the house. Mismatched socks? Toy water pistol? Pthalate-infused sippy cup? French fries? Kid-on-a-leash? Kid-not-on-a-leash? Sledding without a crash helmet? Almost anything might be an invitation, to somebody, to correct you or judge you. Sticking the baby on the handlebars doesn't fundamentally change the game.
The silver lining, though, when you feel whisk of the tsk-tsk, is that at least what people are manifesting -- almost without being able to help it -- is that they give a damn. They care. In public, they care! Look at them caring. It's a spectacle little witnessed in American society, and I think it's entirely human and good. This caring impulse is the polar opposite of littering; littering expresses the basic lack of care. Are we a village or are we not a village? Tsk-ing says we are a village; littering says we are not.
The caring/meddling/judging impulse is one that I saw at close range when I was a kid in Germany. (Where I did not see any littering.) I can testify that Germans, by and large, indulge their inner busybody freely, loudly, and without shame. Especially where children are concerned. Forget admonishing the parent -- a German is never happier, it seems, than when he's nattering at a stranger's child, delivering the full explanation about why bicycles must be walked -- not ridden -- for the next .2 kilometers until the juction of the Fußgängerzone and the Städtebauförderungsgesetz, between 5 and 10 PM on Saturdays during the summer, as clearly marked on the green tiles mounted above the haberdashery. (At least, I think that's what he said.)
Postscript: some people in my neighborhood litter. Some of these same people drag along, and bawl out, young children in a way that just isn't appropriate given the youngness of the children. I'll admit that I judge the hell out of these people; but I can never bring myself to natter at them. Where's a dour German burgher when you need him?