
Yes, 1% of the population means it's rare, but so should be Plane-touched, and they appear to be a far larger section of the population—both represented and not represented, visually— that certainly a few Humans born into Sshamath and/or the Upperdark, is not at all a troubling issue to anyone else. I, for one, understand that such a choice could be a "difficult" or "challenging" RP experience, but one that has the possibility to generate role-play, even if that RP experience is of one of being near-constantly taunted, threatened, attacked, murdered, made a slave, sacrificed, etc. (or at least that is how it is described in the Lore Sourcebooks we have at our disposal). Perhaps the best template for this then is by DM Approval only (something that BGTSCC has moved away from in the last few years, but...)?
BTW, this post is to prove a point: should changes be made to the Server environment because Canon Lore can be bent to support a claim, or, should all changes to the Server come from Role-play. I'd prefer the latter, however...we all know and love—most actually don't love...—that OOC mechanical blocks exist to prevent even certain changes happening THROUGH Role-play. So, of course I am being serious with the top paragraph, but I am also pointing out how it's probably good for knowing how sausages are made.