User blog comment:Gman111/Idea/@comment-1079585-20100228123749

No. They implemented this system in James Bond: Quantum of Solace (a game that manages to rip-off both Rainbow Six Vegas and Call of Duty 4 and still be mediocre), and it is overwhelming. If you save up to buy the best stuff you're stuck with crappy gear for a while, and if you don't then you constantly feel like you are wasting money.

Bad Company 1's system is slightly better, having each unlock cost a single credit. However, they obviously felt that Call of Duty's linear unlock progression was better, as that is how things are unlocked in Bad Company 2, albeit by using specific classes instead of just unlocking things through general XP.