It's not just sex scenes - if you have a taller character, camera angles for almost every cinematic moment will need to be adjusted, as well as animations - characters may need to look up/down to correspond to different heights (becomes especially awkward with a tall female character when everyone's staring into your boobs), and if things such as handshakes or hugs are included, adjustments need to be made. I just finished a playthrough with a male qunari inquisition in DA:I (who is the tallest and beefiest of PCs, for those who don't play DA), and it's frustrating how many angles they got wrong on a game that has been patched several times since release.
It breaks immersion when you have an over-the-shoulder shot which forgets how much taller the PC is and instead of someone's face you get a massive pixellated shoulder in the way. I'd rather limit body options until BioWare have enough time and resources to get them right.
On that note, it's also worth pointing out that gender specific animations are haphazardly used in DA:I - a female inquisitor often male animation in cutscenes, and given how exaggeratedly gorrila-ish that animation is, she looks ridiculous. If you're going to implement gender-specific animations, use them consistently. Otherwise, find a non-gender-specific option that will do.
Personally, I'm happy with femshep as she is. One of the advantages of having limited resources for animation and specific dialogue is that femshep is given exactly the same amount of respect and is in most cases given a very similar treatment to manshep. Do we have to change that? I think she's great as herself 