Actually, in terms of attractiveness alone, the other members of the Advance Team were not any less appealing than Luo'er, but it was Luo'er who had that extra touch of affinity. It's a rare and valuable trait, one that, combined with his already delicate features, ensured that anyone meeting him for the first time would have a very good impression.
That's why, for general receptions, Luo'er was usually the one to step forward. Of course, that he was the Captain goes without saying, but the primary reason was his natural talent for hospitality.
Over the many years of the Origin Project, both Haiya Academy and Shenghua Academy had seen a fair number of the Elf Race hybrids, but few, if any, had been as universally well-received by old and young alike as Luo'er.