I advocate the approach of making the companions and NPC's like the advisers with set sexualities first and then working the romance options around them.
I also want to see bisexual, homosexual or lesbian companions who are not LI's at all.
However, this approach will only result in anyone other than straight males or female having more options if the majority of companions happen to be LGBT.
Looking at a set of nine companions you'd need at least five of them to be LGBT in order to give either gay male or gay females the most LI's, and have two thirds of them to be LGBT if it's to meet my second criteria of also having a LGBT companion who isn't an LI.
If you are just creating characters without LI distributions in mind that is incredibly unlikely to happen, even if you completely ignore real life demographics when creating your characters.
Having major NPC's like the advisers also be LI's makes it more plausible, but the number of NPC's who can have the same word budget as companions is very limited. Even Inquisition only has three, and it's one of the highest scope Bioware games in a long time.