I recently read through the most recent
posting on Massively's Daily Grind column, which solicits opinions on the above question, and thought I'd share it here. Personally, I see no reason why they shouldn't coexist peacefully. For an example of their doing so well, I would point to
Path of Exile. The plethora of currency items which are themselves also used to modify other items means that if you're willing to invest the resources, even a mundane sword can be, well, 'crafted' into something very useful indeed. Just keep in mind the random nature of the process.
Some of the associated comments also lead me to wonder about whether certain other (MMO)RPG mechanics still have a place. Specifically 'roll need/greed/pass' and binding of any sort...