For every Nikita or Veronica Mars on the CW, there have been probably 3-4 Laurels, Lanas, or Caras.
I want to be clear: I am not prejudging Candice Patton's work. In fact, to quote myself: "We obviously don't know how Iris will play out in her entirety in this show." I'm just saying that it strikes me as being perfectly reasonable to fear that her character gets the short shrift, or that she turns out to be more in the Laurel/Lana/Cara camp than the Nikita/Veronica camp.
I have watched the pilot and I am not as enthusiastic as JayKay about the character or Candice. But I still am well aware that a pilot is just an opening salvo and that it takes both the writers and the actors time to develop (or fail to develop) a character. I'm definitely going to keep my fingers crossed. For what it's worth, my personal fears lie more with the writing rather than with Candice in the wake of viewing the pilot.
In terms of males who are cast for their looks rather than their acting abilities and criticism of the same, I would point you to Arrow discussions of the guy who plays Roy Harper. I can't think of too many examples of lead actors on CW shows who struck me as being as weak at acting as the folks who portrayed Laurel/Lana/Cara. Granted, Tom Welling was often underwhelming in his own right, and but when he wanted to, I think he did a good job acting.