It's all emotive thinking, based on a kind of confidence in a utopian solution I guess.
I'm not against left leaning economic policies, but one worry I have is that for socialist types, you can't falsify their beliefs, (in their minds anyway).
If their policies, as far as they can get them implemented, result in social harm, it will just be, "look at the poverty, we need socialism even more"; or they can always look to blame some oppressive power structure.
And I'm inclined to think they ignore possibly important things, (on the conservative side), like whether less "traditional 2 parent family" contributes to poverty or crime.
Or as you mention, mass immigration may place pressure on housing which makes life very difficult for upcoming generations, unless you're towards the top end. It's not the only factor in play obviously, but seems like it could be an important one.
And on crime, they appear too willing to take responsibility away from the individual and blame society. So to fix crime, the real answer, they think, is their socialist agenda.
But if you go soft on law and order, (if it turns out that wasn't such a good idea), the people that suffer most as a result of that policy, may be in disadvantaged areas, perhaps disproportionately minority areas. Or more vulnerable people may be particularly at risk, live in fear for their safety, have to deal with anti social behaviour as a constant background to their lives.