Take the cock nearest to you and grab it. How does it feel to have a cock in your hand? Sure you have had your own cock in your hand a thousand times, but to have a cock that isn't yours in your hand in something else entirely.
Go on and jerk that cock a little. How does it feel? Can you feel it harden as you stroke it? If you are using only a dildo, you don't get that feedback from the cock. Only a real cock can give you the satisfaction of making a dick hard by stroking it.
Stroke that cock for a minute and imagine that cock entering your mouth.