Eldar have been said to been both attractive and alien in their graceful manner to humans since at least 1st edition. This is repeated in 2nd, 3rd and onwards to the modern day. Some authors go down this route, others try and make them more alien, but the standard has always been that humans find eldar attractive but otherworldly. As for your weird, strange notion that the alien is not sexy to humans, sexy aliens have literally been a concept since the idea of aliens existed in popular culture. Early 20th century sci-fi is chock full of aliens that are found to be sexually attractive to humans, either in cnventional beauty or due to weird alien appearances. Furthermore, there are many humans who are attracted to the alien and weird so even if they're not conventionally attractive. Some people got the hots for the Alien from the film, some people eve got the hots for the fucking Robot Monster for fuck's sake. Even in real life examples, some people find sharks, spiders, insects to be sexually exciting. You're also worse than carnac in your interpretation of the fluff, artworks and miniatures in that you throw away tons of conventionally attractive, if slightly adrogynous depictions of eldar (appealing from both a heterosexual and homosexual sense). And if you think Jes Goodwin wasn't pumping both GW's elf and eldar lines full of what he found attractive and cool, you're heavily mistaken. Eldar in parituclar continue to ooze new wave adrogny and strangeness.