Having forwards with good off the ball movement is part of having a creative TEAM, hence the trezguet vs. Amauri comparison. Strikers that know how to move without the ball confuse defenders and destroy their organisation which creates space for the creative passers to pass in. Thats the beauty and sole strength of poachers. Inzaghi, Trezguet, Gomez and their likes are very poor dribblers and passers of the ball but their movement upfront is what allows play makers to create chances. Poor poachers fail at creating space for themselves and they get dispossessed of the ball as soon as it reaches them if it ever reaches them in the first place.
If you have the world's best crossers of the ball aiming at giovinco's head then these crossers' stats would be horrible despite it being Giovinco's fault. Here, the player crossing the ball and the player that should be heading the ball complement each other. A player with great crossing ability is nothing without a player with great heading ability and vice versa. The same thing applies to playmakers and strikers. You can have zizou, Ronaldinho and Pirlo struggling to create assists and/or deliver killer passes if the strikers are all Amauris (players with poor off the ball movement).
So yes I still hold that off the ball movement is part of a team's creativity... its half of it actually.