Preemptive Apology: The rest of this post will be unintentionally heteronormative, as that is the set of experience from which I can best draw. As such, I apologize to those outside the narrow range of sexual identities discussed here for neglecting their experiences.
To put it bluntly, modern society still seems (anecdotally, anyway) to maintain the antiquated expectation that men take the initiative in forming relationships. It is common that we put the pressure on men to initiate relationships ("have you asked her out yet?"), and that we encourage women to wait. While this standard is manifestly unfair to women, as it strips them of yet mode of personal decision making, I posit that it is just as manifestly unfair to men. Taking the first step is bloody hard, after all. You must be willing to put your feelings on the line, to be honest in the face of intimidating awkwardness, and perhaps most frighteningly, to be wrong about your feelings.
All these is leaving aside, of course, the mire of ambiguities and potential misinterpretations built up from cultural expectations of a male privileged society. In any action, one must take into account the cultural context of that action in order to respect the humanity of those around them. It is no different in the case of romantic initiative, save for that the context is that much more overwhelming.
Thankfully, we see the signs of this unfair standard starting to break down, as both men and women alike are encouraged to seek the pleasure of another person's company. In time, then, and with the introspection granted by such discussions as that started by Greta Christina, perhaps we can decouple the role from the initiative.