It's built into the concept I suppose. The soap is about salt of the earth cockneys, so if Albert Square were invaded by the middle classes, with their insatiable appetite for rocket and Victorian terraced houses, the programme would fall apart. So gentrification has to be kept at bay.
Remember Wilmott-Brown? Smooth, charming, a bit posh, tried to set up a wine bar to rival the Queen Vic. Turned out he was a serial rapist.
And more recently there was May - Doctor, wore floral print dresses, went to university, pronounced her aitches. Turns out she was a pill-popping, psycopath prepared to rip the unborn child out of its mother's womb with a pair of nail scissors.
Now we have Stella. She started out as a mild-mannered lawyer. Shy, a bit gauche. Comes from a genteel family. But what's this? Living above a pub isn't good enough for her. She wants to move to a proper house. And naturally, being in possession of materialistic aspirations, she is also a child abuser. Of course she is.
I suppose I can't blame EastEnders. Like all great drama it only holds a mirror up to society. If we don't like what we see, that's not the writer's fault. That's what we bourgeois folk are like. Thwart us and we will murder your children in their beds.