This, no engine is perfect for the job out of the box, you think any AAA developer sticks with an out of the box engine? even if its their own? DICE, Crytek, Epic Games.... all these developers are constantly changing, upgrading and re-purposing their own engines because just like CIG and anyother AAA Developer they also need to make changes for their own game developments, Crytek themselves made a lot of changes to their engine because the one that Crysis 3 was built on didn't work for Ryse Son of Rome, just a couple of weeks ago Crytek released a huge patch for Cryengine 5 bringing in all the changes they made to the engine for:
The idea that any self respecting developer works their game around a chosen engine is laughable, they all work the engine around the game, no developing an entirely new engine is not cheap or quick, the likes of DICE, Epic Games, CryTek..... have developed their engines over more than a decade to get the to where they are today and they continue to develop them for the future.