In a statement posted on EA's official Battlefield blog, DICE clarified that the Physical Warfare DLC pack would be a timed exclusive for pre-ordering customers, and will eventually be released as free DLC for all Battlefield 3 players later this year. The statement also clarified that another DLC pack, Back from Karkand, would be released as free DLC for everyone at a certain point after the game's release, and is not a timed exclusive for any pre-orders or platforms. It's a refereshingly honest and blunt PR move for DICE, directly addressing fan concerns and even hinting they "always knew our pre-order offers for Battlefield 3 would be open to misunderstandings." Regardless, I think the backdraft is being handled very maturely by the Battlefield team, and it will be interesting to see if this can quell the fans' apparently misguided anger.
Source: Battlefield Blog - Physical Warfare Pack available to all Battlefield 3 players later this year