I don't think we need worry ourselves too greatly about their motivation. That's making it an 'us' problem. It is very definitely a 'them' problem.
There's a vast difference between the 'smile love!' variety of public idiot and the bloke in the sauna at the gym for eg. This guy strikes up a friendly conversation whilst we happen to be occupying the same space: ie the pool was freezing today wasn't it?, or 'did you manage to get anywhere near the hydropool today', or 'wow it's busy today, always the same in January' or other pleasantries of that type. The latter variety I engage in frequently. The former I'm less and less tolerant of the more it happens to me, and the more I hear stories of it happening to other women and girls.
Therefore, the usual tedious protestation of 'man-hating' that's regularly churned out on threads like this, doesn't apply. It isn't men I object to. It's the variety of arsehole who thinks women owe them smiles, time, conversation and 'niceness', when all we want to do is go about our day in peace, who deliberately approach women in public to that end, that I have the problem with - and I have a very big problem. Nor do I shy from making that clear.
Cue the nastiness and aggression that immediately comes our way when we refuse to humour their BS. That should tell us something about the kinds of men these are.
It's not us. It's them. I have no idea why so many women seem so determined to pander to this behaviour. I do know that I am not one of them, nor am I going to berate other women for being the same.