D&D seems to take it's cue from Tolkien when it comes to races. There a few important races that are going to show up all the time, and each one has a rich history and acts as a showcase of a different philosophy. Each main race is totally, inherently important to the fabric of Tolkien's setting, and ideally the story goes through the opposing philosophies of each race individually before bringing them together in a cathartic allaiance.
Thing is, D&D is terrible at that kind of storytelling. You might put in a character to show off the dwarf philosophy, but like as not the party will be kill him half-way through and then get lost and end up befriending the orks. Any attempt to tell them about the intricate history of the elves is likely to bore them to tears. The picaresque style of D&D just doesn't work well for a story that goes deeply into the culture of a small set of races.
It seems to me that races in D&D should work more like Chewbacca, in that there is only one Chewbacca. You only see one Hutt, one Yoda, one Greebo. You assume they all belong to a larger species with it's own culture, but it's crucially important that they never explore that culture. Going down to Wookie Planet and exploring the deep history and philosophical viewpoint of Chewbacca's race would be totally detrimental to a New Hope, because Chewbacca isn't there to show a way of looking at the world - he's there to be weird. Showing you where any of the aliens in Star Wars came from would diminish their weirdness.
(Yes, I'm aware that later Star Wars stuff focused on the aliens already introduced instead of making new ones, so all those aliens now have deep interesting cultures and are considered totally vital to the fabric of Star Wars. I'm just using Star Wars as a popular example: the non-humans in pretty much any pulp story are treated exactly like Chewbacca. Inevitably, anything that goes on for a long time finds itself deeply exploring all the things it just hinted at previously.)
D&D, and the pulp that spawned it, fits exactly into this style. The way most travelling-band-of-mismatched-rogues handle race is: there is only one elf. The elf butts in to talk about his crazy elf ideas and propose crazy elf solutions to the party's problems, and he's always doing something weird that shows off his crazy elf culture, but you never see anyone else like him. One is perfect; it makes him uniquely weird.
So, two massive tables; each entry is an alien attribute. One table gives positive attributes, one negative. To be a non-human, you roll on each chart, and the player has to make up their own race out of that mish-mash. This makes the race totally unique, and also makes the player the foremost expert on their culture, not the DM. You could give incentives to keep up an interesting culture by letting them have one or two weird artefacts from the race they make up. You'd want to restrict the number of non-humans - say, one per party, or you only get a random chance of being non-human.
I'm currently in the middle of a Race-as-class DCC campaign, but I might try this out if I get into another game.