I could name a few more features in video games that will never be as good as the real thing.
Hmm, I think you missed my point, so I will now commit the ultimate failure: trying to explain things over the internet
Your example, crafting, is a gameplay feature: I do not craft a +3 Axe Of Being Awesome to hump it (for any strange reason), I make this device to aid in my quest.
On the other hand, romances and sex in Bioware's games are gimmicks of the highest order:
Barebacking Garrus won't help me defeating the reapers -- if only I could get the Illusive Man to my bed too!
Or, screwing Ashley won't do me any good in arguing with Maya, regardless how fully charged super stud I am.
From a different angle: are these scenes at least titillating?
Not quite, I'm afraid. If you want cybersex, you may find much better games - heck, Sexvilla even lets you screw an Elven lady of questionable morals!
Another angle: are these scenes at least humourous?
Again, nix. Fallout, Arcanum and Fable at least made fun of themselves for a good comedy. The only laugh in Bioware's scenes is how awkward they are.
But wait, is there any drama in these relationships?
Absolutely not. Witcher at least tried to make you a bit more human with these sex scenes (while yourself being a mutant abomination in the brink of a bloody war). Fahrenheit (Indigo Prophecy) depicted everlasting love with that sole sex scene. Mind you, these games were still lame here, but they wanted to tell you something with sex.
In ME the only reason to get laid is getting an achievement for not using a condom in deep space. Congratulations.
Romances (the real ones!) are very complex inter-personal actions, defying any awkward simulation attempt in any game. I am in a relationship for 10+ years and my gal still able to surprise me (as much as I am her occasionally, heh-heh).
So...
I think Bioware should concentrate on refining their broken RPG mechanics instead of adding such hopeless stuff.