I agree with WestPablo on this, though I don't really want to argue with Raqball, either. Here is my take.

most young fit females I see on bikes ride road bikes, while a few ride single speeds, and the rest riding old beaters, cruisers, etc...

Second, among those who are in road riding clubs, 95% or more ride some kind of drop bar bike, with a small minority riding flat bar road bikes, single speeds, or converted mountain bikes.

So you have a whole culture among road riding enthusiasts that favor drop bars over flat bars. Now, it could be that Raqball and others are right and all these road riders are wrong, but the more likely explanation is, most people who start out with $500 or $600 hybrids quickly realize the hybrid is limiting them to some extent and they aren't doing as much trail riding as they thought and if they are, they should be looking more for a mountain bike or 29er, not a flat bar hybrid. Do experienced riders move equally from drop bars to flat bars? Perhaps, but not usually in the young fit cohort.

finally, if you go with an endurance type road bike, cyclocross bike, or touring adventure bike, you should be able to set it up to handle some rough pavement or even gravel roads. Just stay away from the really skinny 23 mm tires and go with 25 or even 28 mm tires. They will still be plenty fast, but will be able to handle light trails, which is all a performance hybrid can do anyhow.