As a wise man said, encourage the creative fans; you can only tell one story, they can write a million (and promote yours in the process). From that point of view, Astarion (and Halsin!) are excellent ambassadors to entice new players, even if once they are in the game they discover Gale's charms and culinary prowess.
I would also like to take a look at Larian's data, because in the same breath as they released the romanceable "favourites" they said that 75% of the players chose to behave honourably, which can lock out Astarion and Lae'zel pretty easily. Lae'zel's quest is very unfinished, and you don't need her in the party as much as you need Shadowheart, a healer... so that also decreases your chance to interact with her.
So, are the players actually going for Gale and Shadowheart or are they just settling?
