Given the trend so far, I expect Inquisition is going to include a brothel. And maybe it's too late now for any changes to be made, but nevertheless, I am requesting that, going forward, Bioware consider humanising their prostitute and stripper characters (maybe include one as a party member?), and presenting a more nuanced, multifaceted and, above all, accurate view of the sex industry and its workers, rather than using it as an avenue for player titillation and cheap jokes.
I'm sympathetic to your idea; sex work is played for cheap laughs in most games, when actually it can be both darker and more complex.
But you do run into the problem of comparatively minor characters, who you actually aren't meant to know all that much about, suddenly giving you their life story. If you're familiar with Blackadder II; "Look, if I'd wanted a lecture on the rights of man, I'd have gone to bed with Martin Luther." Maybe a quest where you help an unhappy sex-worker find a way out, like you could with Athenril's indentured lad in DA2. Or maybe a quest where you gain an apprenticeship or patronage deal at the Pearl for someone who wants to get into the business, but doesn't want the dangers of street work? Or setting up a promising lad or lass with an Orlesian bard, so they can learn the metaphorical ropes? Do you have any ideas for how to do it without getting too heavy handed?
There's also the Firefly approach. I know it has its problems, but making sex work a legitimate, regulated business where you learn your trade before you ply it, and have to answer to a guild might be one way to go.
It'd be hard to write, and it'd be particularly hard to write a sex-worker companion, because the skill-set they would be using as your companion possibly wouldn't involve much sex-work. Even though Bards use sex in the course of their intrigues, their in-game skills are more about the singing and distracting ...