Sawyer had this to say re: combat and non-combat skills being divorced from each other -
It's essentially a variation on respecing. Instead of allowing an arbitrary respec option at some point in the game, they're going to lessen the possibility of screwing up a build in the first place.
Not necessarily my favorite idea ever (I think cRPG customization should be open-ended enough to allow for the possibility of an 'inferior', stunted build), but it remains to be seen how it'll work as we get more details.
It also depends how the XP system will work exactly. We know that combat and non-combat skills will use different currencies; if using a skill in a specific category propagates skill gains there in particular, then it could be limit jack-of-all-trades scenarios (i.e. actively using non-combat skills and solving conflicts without fighting nets you much more non-combat XP than combat, and vice versa).