No, transwomen don't HAVE to be really cute and indistinguishable from a normal girl, but people who are open to dating transgender people have every right to prefer only ones who pass.
And IMO, what they looked like prior to their transition is absolutely important, at least to me. I would not, for example feel comfortable dating a transwoman who, at one point had more facial hair than I do, or in Riley's case had a large Adam's apple.