I definitely agree with this, on paper the whole thing reads a lot more Gwen-like, it's like he drew up the ship before S1, left it to develop in another direction, and then transposed it onto Ianto because Ianto just happened to evolve into Jack's love interest, so he gave Ianto the function Gwen was supposed to have and the feelings and motivations that Gwen would have had in the ship. It's fucking lazy.