Gamerant's Andrew Dyce posted a new article for The Witcher 3 that talks about the delay, and quotes the developer saying it's because "The Open World Was Missing"
More information.As one of the very first games confirmed to be coming only to next-gen home consoles, CD Projekt Red set expectations for The Witcher 3: Wild Hunt even higher than they may have been on their own. But after putting on an impressive show at E3 2013, the developers announced that the game would be delayed from its initial release date, hitting store shelves on February 24, 2015. So why did the team need the extra time? According to the heads of development, the game’s open world just wasn’t up to the level they demanded.