Chris....

You just explained the reasoning behind the Masquerade, the Veil, the Mists, the Fog, and whatever the hell it is the Mages have. Simply put, the regular mortals outnumber the supernaturals. However, the games focus on the supernatural creatures for a variety of reasons, including personal horror, the search for humanitatis, control of your own hubris, etc. After playing a supernatural creature for a while, if done correctly (not to sound pretentious), it may just teach you something about being human.

Besides, sure - there are more humans, and if they found out about the supernatural, they'd want them all dead. Downside is, the logistics of having that many "people" in game are simply astounding. So, supernatural critters it is...with the occasional mortal.

jim