This did happen. I was recently replaying ME3 with a FemShep who romanced Kaidan, then stayed "faithful" through ME2, and was rekindling the Kaidan romance in ME3. Then, after the "Cerberus tries to take over the Citadel" portion of the game, I was returning to the Normandy and there was Kaidan asking to be reinstated (or Ashley, if she was the Virmire Survivor). If you accept him back and are in a romance, he will turn to board the Normandy and you get a zoom-in of FemShep checking out dat booty.
Granted, I also acknowledge that may only be in there because of MaleShep checking out dat Ashley booty, but still... it was romance acknowledgement that involved a female ogling her boyfriend, and I fully supported that as being a nice, equal option. 
So the sex appeal for dudes was unskippable and in the main game and sex appeal for women was found only if you're in a romance with that specific character? That sounds about right for Mass Effect.
I dunno Jacob as well as Veda really missed the mark with me. I know they both had macho muscly man shots... Was that meant to appeal to women?
I was really surprised to learn that Thane was created by women. I have a hard time imagining why an older guy who carries around detailed memories of his beloved wife and is terminally ill and has weird lizard eyes could appeal to anyone....... 
It's interesting to kind of see what women find attractive versus what men or women THINK women find attractive.
Same. With Jacob and Vega, I wasn't interested at all. I liked the fake-flirting with James because to me it sounded more like Shepard was calling him on his bullshit and putting him in his place. It's playful and kind of a cute friendly relationship. But everything with Jacob? Eh, no. I don't think waving a bunch of muscles in my face and inappropriately hitting on people who clearly don't want to be hit on is going to do it for me. I never particularly saw Jacob as sexualized the way the female characters are either, but maybe that's because I was so put off by the game trying to convince me I should be into him that I generally avoided him.
Thane being written by a woman doesn't surprise me in the least, actually. He is a walking tragic hero trope. He is sensitive and deep, but cool and dangerous. He is solitary and frightening, but he lets Shepard in and shares his feelings with her almost immediately. He can kill a man in seconds, but he's vulnerable. Thane is 100% romance novel trash and I don't care. The first time he appeared on screen I turned to my roommate and said, "Oh no. Oh no I love him."