Just because you and your brothers may automatically have sexual thoughts about girls you're attracted to doesn't make it the same for every guy. I'm not a guy, and I don't talk about this stuff with my friends who ARE guys, but I know them well enough that they DON'T have sexual thoughts about girls they're attracted to. Well, they may have a couple but it's FAR from all the time, or even every time they see the girl.
Not to belabor the point, but I agree with you that it's not the same for every guy. As a male, who definitely discusses this with his male friends/relatives, it only applies to the vast majority of us and anyone I've ever spoken to about it in person. Just for future reference, you refuted what I said by saying "Well first of all, I'm not a guy and I don't really talk to other guys about it, so I really don't know what I'm talking about, BUT here's what I think anyway." This is not the best way to begin an argument.
"Hey guys, I'm not a doctor, and I never talk to other doctors, but I think we should amputate."
Just to throw down the gauntlet and let anyone who's interested in facts and scientific studies instead of all these random strange opinions, etc...
http://www.kinseyinstitute.org/resources/FAQ.htmlThat site is basically the bible of sexual research. An excerpt:
"54% of men think about sex everyday or several times a day, 43% a few times per month or a few times per week, and 4% less than once a month"
And that's just sex. I couldn't even find a study there that asked how often men look at attractive women's bodyparts. It must be such an incredibly high number that it's off the charts.
Getting back closer to the topic: Yes I can see that people are picking out the handful of times that Vin and Elend show affection towards each other, like the honeymoon...2 years after they met. I would hope these scenes exist somewhere within the 2,000+ pages of text (paperback) otherwise there would be little evidence of any type of physical attraction/relationship. It's the fact that everyone looks to the same handful of scenes that demonstrates the point that there wasn't much there.
Ultimately it comes down to whether you noticed the lack of sexuality in the series and whether you thought it could use a bit more to add to the depth of the characters. Even outside of Vin and Elend, the other characters you mentioned never talked about the opposite sex or 'had thoughts' beyond "He/She is beautiful, has shiny hair, is smart, I love him/her." It's definitely a very high-minded view of attraction and love, so if that's what Sanderson was trying to accomplish on purpose, I'll give him that. It just wasn't the most realistic or interesting angle he could have chosen. A very minor complaint.