We have topics over topics discussing AA kissing animation or Shadowheart liking Halsin, but very little discussions about the personality or character of them or others.
Personally, I don't think the problem lies in romancable comanions themselves, or that romancable companions can't be interesting. It is just that if every RPG game makes every companion romancable, that greatly limits a potential range of your companions. While I understand that characters like Wynne or Stren don't generate as much "engagement" as shaggable cast of Dragon Age, I do think they are an important part of the puzzle.
The issue isn't in every companion being romancable. It's the focus on "Romance = Sex".
Thus, every companion being romancable, means every companion must be sexy so you can have a hot sex scene because that's all that most games make their romance system about. Get approval receive sex.
Romance isn't entirely about sex. But that's as deep as any game really goes.
It's somewhat refreshing in Rogue Trader where you have a character like Yrliet whom finds you (And humans in general) utterly repulsive. Yet you can have a romance with her, one that exists based off a spiritual connection. 2 kindred souls coming together to find solace with each other. It's not about sex, but about having a deep connection.
A game can have a diverse cast AND have everyone romancable, if romances aren't all just the same old shallow sex focused systems.