The following comes from an ONM interview with Hisashi Koinuma, vice president of Tecmo Koei.

"I think our success comes from considering what is best for every (Dynasty Warriors) title, and from never giving up on advancing. There are parts of the source material and also of the Warriors franchise to which we have to remain faithful. We think about the parts that are valuable to each. What is important is that the end result is very good for both properties." - Koinuma
Link