Nah...it's simple.
A six man group needs some certain creatures, the rest is coincidence.
The leader was of course him, and Sabine probably searched for him (any hot chick - every party needs one - would work as Haley's opposite). Then they need a tank, where a barbarian half-orc fits perfectly. (which is not sooo much an opposite to Roy, except for his IQ, but many fighters are dumb (sorry)) The they need a wizard, which demands an elf/half elf/drow. And a drow is the best fit for an evil wizard. Furthermore a cleric is needed, and dwarfs are good clerics, having high CON (Nobody wants a cleric who's faster gone then the ones he's supposed to heal). It being a girl might be sheer coincidence... Finally a tracker's needed. That's the only thing, which might be a strange coincidence, though I cant remember Yikyik's class or purpose ever being mentioned...