maybe you over estimated how many people actually want to play tiefliings?
I think the "issue" is probably mostly that races have very specific stat bonuses and classes are stat-dependent.
Optional racial features, like free skill training and armor-weapon proficiences ( Armor for dwarves, perception and swords and bows for elves, sneak for halflings, etc ) darkvision, free spell-like abilities or free spells like the ones the gith and high elves get, features like the superb halfling "lucky" have, etc etc usually outclass the stats of the humans for most of the builds; since humans have none.
I think choosing human is more a rpg/preference decision, because mechanically usually there are races better suited for your class.
