While I agree with some of that Noel, I believe there's another side to the cards then just the TV world. I personally think the reason cards are used as opposed to any form of Evoker is because the characters have faced and accepted their shadows, thus having a much closer connection to their Persona. The card is effortless, easy, natural, as it is meant to be for one who's gone through a major ordeal in facing their darker selves. An Evoker takes effort to use at first and drags your Persona out without any kind of test required, it's sorta like an easy way out. I've always thought the Evoker was an artificial, man-made way to coax a Persona whilst the card was a natural, more graceful method that shows the connection.
Anyway I'm not disagreeing with you at all, just my two cents on the whole Evoker vs Card thing..............
I'm being a know-it-all, sorry.