That sort of subtlety would work when the whole story is about city elves and you can sort of build it up... but when having to pack things in tightly to one origin story to give you a clear view of how things work in your former life, especially in a dramatic and violent way, I think this one worked well enough.
Aside from needing to harden him if he's made king, I don't see anything that was more significant than what my Warden jumped through to romance Leliana.
See, that is where you are wrong. You don't need to build up to it. Having the noble tear through on a drunken rage, ruining their celebration and smacking a few of them around, calling them names, even saying he owns them, creating an environment of fear and oppression gets you a very clear image. Then maybe he abuducts Shianni for attacking him. You don't even need to have her raped. The implication that he was going to teach her a lesson while keeping it very grey area as to what he was going to do and having the guards go along with it would more than suffice. It created an environment of terror, shows the oppression they face, the racism, the mistreatment, the abuse of power... if that doesn't get you to see things clearly then you are daft.
Edited to add: The option I just presented is far more dramatic and overall terrifying that what they did. Now we see the elves, overall, aren't really even safe in the alienage. We see that anyone could be grabbed for whatever reason and the guards back it. We see that they are mistreated and abused and it is allowed. It's an environment of fear and oppression and mainly happens because they are elves, once property of the humans.