Remember when Halo 3 had an exclusive beta with Crackdown? Chances are a lot of people bought Crackdown specifically to nab a copy of the beta without realizing the game they bought was actually worth playing. As it turns out, Crackdown 2 may have suffered that same fate if not for the release schedule of Halo: Reach.
In an interview with CVG, James Cope, Producer of Crackdown 2, said that the title was initially in consideration for inclusion of the Reach multiplayer beta in retail copies of Crackdown 2. Cope stated that, "We would've loved to have done it, basically. We would've absolutely loved to have had that opportunity but the timing just wasn't right for us."
Sure it's all well and good that the Halo: Reach multiplayer beta would have boosted sales, but Crackdown 2 should be able to sell based on its own merits. There should also be no problem in sales if it promises to deliver even more than the original Crackdown did.