The Complete Book of Elves has a dilemma. Well, it has a lot of dilemmas (like, for example, the fact that its central dilemma is both interesting and dangerous), but its most important one it never quite resolves. Hell, never quite acknowledges. But, of course, it can't do either of those things, because to even state the dilemma is to make it quite instantly obvious how far out on a limb you actually are.
The dilemma is this:
Choosing a race in the AD&D rules is supposed to be largely cosmetic, with advantages in one area being compensated by disadvantages in another. And yet, the setting background of many AD&D worlds calls for elves to be explicitly and objectively superhuman.
Man, I really wish I were somewhere else right now. Ultimately, The Complete Book of Elves has a bad reputation because it dances around its dilemma in a really clumsy way. It never comes out and says "elves have such profound advantages that if they were mechanically represented in an accurate way, they'd unbalance the game," so a lot of the elf swagger here comes across as really noxious fantasy racism. But it also kind of gives elves some unbalanced advantages based on the assumption that the fiction is accurate, so it kind of looks like the book is biased towards elves.
And honestly, I don't think there's a version of this book that could have ever worked. What we got was super muddled, because it's trying to serve two agendas at once without ever spelling out exactly what they are. But the only way it could ever have been even remotely functional is if it had done something like, "imagine if you will, a world where there really is a master race . . ."
Under the best of circumstances, this is a situation where you go, "whoa, okay, let's just calm down and talk about something else." Here, in this book, where (all non-evil) elves are presented as extremely white (literally - it points out that elves don't tan and have pale skin "by human standards" in that unfortunate way 90s D&D had of forgetting that human skin comes in a whole rainbow)?
It's to this book's advantage that it's such a mess, because if it weren't, it might be as offensive as hell.
A more responsible fictional medium could get some mileage out of the idea of superhuman elves. When we think of the continuity of the great tree of life, and how the meritorious qualities of the mind vary from human to ape to mouse to flatworm, then it is the height of arrogance for us to put ourselves at the top. There could be some form of life whose mental powers are as far beyond our own as ours are beyond a dog. And even to the degree that we'd have a friendly relationship with these super-people, it would be, from their perspective, like the relationship between a master and a pet. We'd relate to the person-like qualities they demonstrated as the shadow of their thoughts fell across our lives, in the same way that the instinctual mind of an animal can appreciate a treat of food or word of praise, but we could never know their true selves, because the bulk of their concerns would be of realms we cannot comprehend.
But tabletop roleplaying is not generally a responsible fictional medium. So much of it is improvised, spoken from the gut. It would be hard to convey the advantages of this speculative higher-order thought, and harder still to not simply have those advantages recapitulate your own prejudices as a player.
The Complete Book of Elves doesn't even try. Its approach is sort of the inverse of what we saw in The Complete Barbarian's Handbook. "Barbarians" don't get the Weaponsmithing skill, they get the Crude Weaponsmithing skill. They don't get Artistry, they get Primitive Artistry. Everything they do is just a crummier version of what "civilized" people do.
Everything elvish is better than its human version. Elvish cooking is more subtle and refined, elvish music more sublime, elvish craft more beautiful and distinctive, elvish fighting more graceful. I find it less offensive than Barbarians, because I can imagine that magical creatures might have a magical way of doing things, but it's funny to me how this book has a reputation as presenting elves as super racist and for all the wrangling about social justice in rpgs, I've never heard anyone disagree with that assessment.
(Ha! Take that, western civilization! It's not so fun when the shoe is on the other foot.)
Seriously, though, the elves in this book are super racist. I wonder, though, whether this fantasy racism has the same pathology as the Barbarians book's real world racism. If you view all human artifice in a framework of "progress" and "advancement," then maybe you'll feel tempted to pit different cultures against each other in a kind of hierarchy of technology. The dwarves have superior steel-working, but the humans are the best at traveling the sea. And because in many arts, you can establish benchmarks that are more or less objective (a steel weapon really is better for most applications than an obsidian one), there might be a temptation to extend these comparisons to the cultures themselves. It's not something that's necessarily fair or just - especially when it comes to cultural products like art or music - but if you fell to that temptation, it might seem perfectly natural that a culture that excelled in all the fields you care about would be "superior" to others.
Let this book be a lesson to you, then. If you go that route, people will, with complete justice, think you're a huge racist.
Also, that thing about the Drow getting their skin turned black as punishment for being evil? That's just super fucked-up, no matter which way you slice it. Bad TSR! Bad!
UKSS Contribution: This is tricky, because I'm stuck with the same dilemma as this book. If elves are just people, then as a fantasy race they're barely distinguishable from humans. They're the guys who wear green and have pointed ears and live in the woods. That's not much of a niche.
But if I make them inherently magical and mysterious creatures, then what, their shtick is that they're "humans, but better." I blame Tolkien, who inspired D&D elves, and thus led to a hundred different writers homogenizing the concept so that the wild edge of the original myths was almost entirely smoothed away (although, like many of these situations, Tolkien's elves were much weirder than those drawn from his work).
I think if I go back a step, to the original Alfar, that's a concept worth salvaging. They look human, but they are of the same stuff as the gods, and in fact are lesser gods of nature and fertility themselves. That will be the true nature of Ukss Elves - they are gods with human shapes and near-human scale.
But what about The Complete Book of Elves? What godly inspiration did I find in that? I'm going to go with a really shallow cut here. Drow. But only superficially. There will be black-skinned elves in Ukss, but I'm going to give them an entirely different culture and social role. I'll try to keep them as recognizable as possible, but I feel like I have to compensate for how pale the elves in this book are.