I think it’s very hard to build those close non-related relationships (Irene and Chris or Max and Colleen) when they we no longer have everyday soap scenes, instead we are constantly in high drama. Having related characters makes it easier to see why they care for each other, and the lengths that family will go to for each other. The most recent family relationship that has boomed in years has been Roo and Martha - look at the moral dilemma of the kidney story.
I think close knit relationships are hard to find nowadays because we have so many waif characters. Of the 22 current characters, they have 18 different surnames.