Given the same budget and time frame when you don't have to develop the games engine you have plenty of time to fix both bugs from your code but that natively in the engine. Properly developed you benefit from upstream commits to the engine (bug fixes, etc) from the engines developer. In turn the subsequent developers are submitting their fixes back to the team managing the engine. Everyone benefits from everyone, but merging commits has its own little nightmares.
The amount of work put into a game based off another engine can vary depending on whats being done and of course the engine itself. Obviously Black Box had a lot more work to do making Need for Speed using Frostbite 2 than dialing in weapons physics, making maps, soldier skins and menus.
EA said fuck you DICE in 2004. Anything DICE develops is EA's property to share with any of its studio's and EA most likely has the DICE engine architects doing work for other studios on a full time basis. EA having Danger Close develop the game using DICE's engine also meant they could slash their budget, make their time frame shorter and reap the rewards in profits.
I find it sad that there was probably a kid in sweden that fell in love with 1942 and wanted nothing more than to become a game developer, even worse work for DICE. If such a person did succeed they ended up working for a company that was taken over and now goes home every other day hating their job, hating what they read on the internet about they job they do.
Who knows who made the call on VOIP. But no 2143 was a direct call made by EA i guarantee it. EA wants to own every single game studio run by Activision. Those they can't own they want to compete with and compete with hard. It means doing any damn thing they think it will take. 2143 would be a fucking hit (BF3 haters wont like it), but EA thinks Battlefield 4 is going to bring in that CoD cash and thats all that matters.
Jus' Sayin