Reports that this information was not presented on Paradise's box are false, as the back of the box lists the hard drive requirement for online multiplayer under the game's features (as seen above). EA support representatives state that the temporary storage space required for online play exceeds that available on the Arcade's included memory card, making the hard drive necessary.
Of course, this isn't new information by any means. Several already-released games require the 360's hard disk drive for online play, including Crackdown and Final Fantasy XI. The problem is that while this information is presented on these games' boxes, it's not presented as clearly as it could be. And for online shoppers, the hard drive requirement isn't listed at all. Sites like Amazon.com and EBGames.com fail to list the hard drive requirement in their product descriptions of Burnout Paradise, and never include images of the back of the box as part of their product pages.
While EA can likely not be held accountable for the hard drive issue, online retailers should be responsible for sharing all relevant information about products. That Amazon and GameStop/EB fail to mention the hard drive requirement is a serious problem, and while consumers should be more careful about researching before purchasing, this process should be made easier by sellers, and not more difficult.