It was obvious that the show thought Mick would be iconic because he was played by Danny Dyer (who is not even that popular with the British public), and that the Carters would be iconic because DTC created them and because they are related to Shirley (again, never all that popular of a character). And some fans do like them, but ultimately they're irrelevant to the canvas. It doesn't help that none of them have interesting relationships. I see some fans say things like Dean has to die so we can get the good times again between Shirley, Mick and Tina, and all I think is - why is Shirley's vile behavior forgiven just because Dean dies, and when did those three ever have an interesting relationship to begin with?
I hope that like when that hack Collinson left Corrie and the Prices were phased out, the same happens to the Carters.