To PS3 platform loyalists, the general amount of crap talk from Epic (more specifically from their always opinionated developer face, Bleszinski) doesn't exactly endear them to PS3 gamers.
Of course for most, a good game is a good game worth a first day purchase and in the case of Bulletstorm, it was simply bested by KZ3. People who owned a PS3 went with the better game. Or maybe they also bought Bulletstorm for their 360 or PC; it just didn't steal many sales from KZ3.
Epic may well have been better off selling the game to MS as a MS platform exclusive (Xbox/Windows) had MS offered them a big payoff for even a year of exclusivity. Maybe no such offer was made. From MS' perspective, maybe marketing Bulletstorm as a MS exclusive could have helped generate more hardware sales with more "only on Xbox and Windows" ads. Or maybe they just didn't deem the game as important enough.
400k combined are good first week sales, but paying a substantial amount for an exclusive release plus MS marketing to emphasize the exclusivity probably wouldn't have been worth it to MS for an additional 60k unit sales that ended up on the PS3. So maybe it was better off as is.
