I think Cullen would be more likely to judge based on physical features than Alistair actually. For Alistair I always thought the romance was more like we've been through all this misfortune and chaos together and we're still alive... He doesn't have that connection with anyone else.
You think Cullen in shallow? Hmmm...I'm not sure. He's been through a LOT and judging someone based on initial instincts has always gone badly for him. DAO, yeah he was young and narrow minded, DAI, I think he knows there is so much more to a person than if they carry a staff, sword, or have pointy ears. And didn't they only race gate him because of a technical issue with height? Or they ran out of time? He could've loved you with horns too