A couple of patches ago I had a white Fuscina that I used on my barb. I can't remember what the DPS on it was but it was better than anything I had been able to find or craft for a 1-hand weapon. Really looks cool, too. I have really been hoping to get a magical or rare fuscina but it hasn't happened.
I give my merc only whites, so they're definitely good for that. I don't waste blues or rares on a merc.
Just later in the game, enhanced damage mod spawning on blue items will be higher, so it will be nearly impossible to find top tier (for that point of the game) white item that deals better damage, than even 1-2 tiers lower magic item, but with moderate enhanced damage affix on it. This situation where white items can be useful when they drop, occurs only in very early stage of the game.