Don't understand some of the complaints about the new sounds. It's not like the original was this bastion of amazing sound.
With that said, I would not be surprised if the use of the AW sound effects for capping flags and things like that are placeholder. CoD Multiplayer reveal builds tend to be older and use placeholder sounds and animations for
some assets until the final release, where they can often change. For example, MW3's Kill Confirmed announcer at CoD XP 2011 was a complete placeholder generic voice, but the final release included the faction announcer calling out "Kill Confirmed!" whenever the tags were picked up. Here's an example of what I'm talking about with placeholder assets:
https://www.youtube.com/watch?v=Bjk2_2D_LLw
Not trying to get people's hopes up and it doesn't happen often, but you never know.