I agree, what sounds good for one genre might not sound good for another. I think playing with a pick sounds good for most metal genres, mainly because of the sharpness of the sound. But of course equalization has something to do with it too. You can immediately hear Mendez plays without a pick because of the rounder, warmer sound, but with most (death) metal bands you only get the low boom of the eq and high "twang" of the pick. Different playing styles for different genres I suppose.
Pointless rambling on? Maybe.