So anyone want to know why exactly COD came to be by the same devs that made MOHAA?
Well, classic tale of EA being money grubbing ********* and giving the developers little to no respect.
Back in the day the 2015 devs used to post on alliedassault.com, both during and after development. When the game was finished it was obviously a big success (bloody mp was still going near 15 years later so that says a lot even though it was a very late addition, originally it was SP only). Anyway 2015 were initially going to work on the expansion (Spearhead) then next thing we know they're dropped and its EA internally making it. According to one of the devs i spoke to EA were basically being incredibly tight with money and not giving 2015 any creative freedom. He likened MOHAA to making a big budget movie with a "made for tv" budget, 2015 wanted to put some of their own ideas into the game and EA wouldn't allow them.
So, soon after some of the key devs left 2015 to form infinity ward and the rest is history. COD was a massive success, EA internally kept trying to make sequels to allied assault like Pacific Assault and Airborne, both met with "meh to average" reviews (though airborne was much better than PA). They even talked about Pacific Assault having something like 200 devs working on the MP alone and it was more like a standalone game than simply a multiplayer component. There were a lot of rumours at the time that Pacific Assault was almost completed, then it was scrapped for being overly complex and the game restarted again, which is why it came out supposedly later than EA wanted, the tech demo below shows quite a few features, barely any of which made it into the final game, these are allegedly what was meant to be in the game before it was scrapped, simplified and restarted (having numerous ways to take on a level and not going along predetermined paths is a very obvious omission). They even shoehorned in a brothers in arms type command system at the last minute which barely worked properly.
Somewhat ironic that the most successful Medal Of Honour game wasn't even made by EA, suppose that says a lot about them on the whole. Had they let 2015 get on with the expansion and tossed some more money their way their franchise still might be alive today instead of being shelved around 5 years ago and COD might not ever have been made.