DA2 companions were playersexual and in that game you still couldn't romance Varric. But yeah with DAI they went all in with the "this character has particular gender- and race-preferences", which helps them to sidestep any potential problem elements. Though 3 consecutive games where there's no dwarven npc with a romance scene is clearly a intentional decision on Bioware's part...
Hmm... Seems like you're correct! :] DA:O only had male/female limitations for some companions. DA:I had certain limitations (Solas and Cullen), but other than that they were mostly gender-specific yet again. :] I didn't play DA2 (and may or may not have completely forgotten about it's existence... :| Sorry) so dare not comment on that one. My bad!

Well, no point in looping the conversation by repeating myself more than I already have, so I'll leave it at that. :]
I think it just really comes down to the models. If the models look like children, that's problematic. If the models look like small adults (dwarf-, human-, or other-like), then that's fine honestly. Short does not necessarily mean child.
100% agree.
I think it's a Tolkien thing that female dwarves have beards...?
Ooooh, you're correct! If I recall it right, all dwarves had beards (or at the very least very bushy sideburns) from early on in Tolkien universe. *thinking* I even remember Aragons comment about it in "The Two Towers" (EE) now when you say it. ... ... *shudders* :|