After the last year implementations' of new races, which have been quite nice, there is still one glaring absence: the half-drow.
This race has always been contemplated in 3.0 Forgotten Realms, starting from the very first campaign setting released.
It is the only and last one of the core races of that setting that is still missing now, unfortunately.
Its absence is also particularly strange, because if there was a setting where half-drow would be numerous it would really be one like Areith, where drow live in a multi-ethnic town, in which they do not have a significantly higher standing than humans, and where mixed relationships have flourished over the years.
I don't really see any hindrance to allowing them. Anything a halfdrow can do a human outcast or a drow can. They would still bear a social stigma often comparable to drow, so there would really be nothing new.
Maybe Crinti half-drow could have a slight restrictions, or even not allowed to be played, but regular half-drow should not pose any significant problem. Bring them to the island at long last, please.