Is that the point of publicly available mugshots?

Mugshots, like fingerprints and now DNA, is opportunistically collected because it makes policing in general easier (you can stick "10 most wanted" pictures in the post office, if they still do that). Wanted posters with photos of wanted miscreants go back to the 1800s and drawings before then. As seen on TV they are used in mugshot books -- I wonder if those books ever have any value in the real world?

So no, I don't think that is the point, per se. But I think they do make it more likely that someone will say, "hey, DiggyJohnson, isn't that your uncle Fred?" If you're in a revolutionary or criminal group you might scan the arrest records in text, but if you don't have a specific reason, you're unlikely to but might recognise a photo.