Would your view change if Cullen was somehow a mage or had a deeper sympathy for the mages?
I ask because sometimes I do think people would tend to get involved romantically with characters who share their beliefs.
Not just that, but it would help. If he were gay, I would definitely try a romance with him, but I suspect that I just like Dorian better. Cullen, to me, is the opposite of Solas. Cullen is physically attractive, but has a crappy personality. Solas has an amazing personality, but isn't very attractive. Dorian has the best of both, for me.
They haven't.
Dragon Age: Origins is the only Bioware game I can think of where there were equal numbers male and female love interests.
And ME2, which had a 3/3 gender split. But yeah, those are the only ones. Every other game (not sure about NWN, off the top of my head) out of the 11 games with romances were uneven.
I'd also like to point out to all of the people who are saying that Vivienne must be an LI because they would never split them unevenly that many people said the same thing back when we were speculating companions. "There's no way that they will have only 3 female companions out of 9." Look how that turned out.