Let my point out that the premise of including crafters and gatherers does
not preclude the concept of challenging and epic stories and missions. Currently the major story arc is solo-only, and thus the combat is toned down to a point where it is trivial for a combat class. When group-based quest content is added this need not be the case.
So far the concept of crafters and gatherers as fully realized classes in their own right is new, and there is much to be added to make it a complete system. Let me point you
here for one concept I've had about how to make exciting challenges that
require a diversity of classes to succeed.