some come with a rubber grommet that is higher then the head of the screws.. so you can't bash your toes on the screw head itself.

The screw heads only get sharp when you bur them with the screwdriver.
You can smooth them off real easy with a file. Just run it lightly over the top a few times until the sharp bits are gone. You should do this whether they are covered or not because if there are sharp bits on them, you will eventually cut something. A finger, a foot, a face, an anything.