Character generation in a lifepath system is pegged to the setting. I want the setting to be modular (even though we have a default) so it makes sense for the new book (with character generation, campaign and basic setting tie- in) to be separate from the combat rules on that basis as well.
There is also the fact that the combat rules has been out for many years ‘as – is’
In spite of these reasons we may, however change the name (again) and / or merge what is now the players guide with core rules in the future, in part we wanted to get player feedback on it. Regardless, it will remain the same for a while we don’t want to change it every week.