The brake vibration on my 04 accord got pretty bad so I just bought and replaced the rotors. Afterwards the brake pedal went all the way to the floor, so I bled them, and it didn't make any difference. Then I noticed they are literally 1/4 inch thinner than the old rotors. I'm also reading that new rotors are made thinner than old rotors, but I assume this is for new cars not replacements. Did I get sold the wrong replacement rotors? Everything else fits fine.

 

You might have the wrong rotors for your trim level. Accords of that year had at least 2 variations on front rotor size. a 282mm diameter with a 23mm thickness and a 300mm diameter with a 28mm thickness.

Engine, transmission, and number of doors seem to influence what size front rotor the car has. I didn't look into the specifics, you will need to look at the notes on the rotors and make sure they agree with your car's configuration.