No, it seems the "Hinata is owed Naruto's affection" is the unspoken reason adopted by NaruHina supporters.
"Look at all this! He went nuts when she sacrificed herself to save him in the battle with Pein." Yes, but had it been Rock Lee, or Kiba, or Shikamaru, even Ino.... seeing a friend die for him is one of Naruto's worst nightmares. Of course it would send him over the edge. Also, he never acknowledged Hinata's confession.
"She had more panel time when he saved her from the Zetsu clone than when he saved Sakura"- yes, but because, for Sakura, it wasn't a huge development for her. Hinata, however, had this scene as the stepping stone to her next... the inner monologue stating she wouldn't chase him after the war, but would be beside him.
"Hinata slapped him to bring him back when he wavered, and then he held her hand"- yes, to transfer Kyuubi's chakra. As romantic as it may look, he STILL has not acknowledged her romantic feelings for him. Honestly, I feel really bad for Hinata... I think that Kiba, whom she cares for deeply as a teammate and his bond with her is similar, would be a better romantic development for her.
I think the dominant gender thing was the "shounen manga" bit? I'm not following there, either, to be honest.
But it has been stated by Sai, Yamato and I believe Kakashi as well that Sakura is in love with Naruto. She probably just doesn't realize it yet... like Naruto, she's a little hard-headed at times and she did seem downhearted to learn that Hinata was in love with Naruto. My idea on that bit may be that Sakura, while still pining after Sasuke but starting to develop feelings for Naruto, realized that Hinata loves Naruto in such a wholehearted way that Sakura herself can't really compete. She then realizes that, if Naruto is taken, that leaves her with the far less honorable Sasuke. That's probably why she thought of him instead of Naruto when that other shinobi asked her out- in her mind, Hinata had spoken for Naruto, and until Naruto says otherwise, he's off-limits.
But I wholeheartedly agree that, as far as romance with this generation of ninja goes, it's all unrequited love, baby.