Well I ultimately agree with you in that fiction is full of drones that go down by the truckload under the flashing swords and crackling spells of heroes. No problem there.
Its the idea that giants, demons, and such powerful creatures can be mooks I have a deep problem with. I can see the average town guard having 10hp and going down with a single good shot from a high level hero (I'm not saying I can see them being taken down in the same manner by Jackie Chan wizards....that's weak). I have yet to see any precedent in any fiction that would presume to claim that it is good storytelling to have 16'tall giants being killed like they were 5yr old human children no matter how badass or full of moxie the heroes are.
I can't recall anything other than orc like cannon fodder going down by the dozen by powerful heroes. I can't see dragon, fire giant, vampire, ice devil, balor, or equally powerful creatures being one shot ever no matter how powerful the heroes are. If the PCs should be able to kill such powerful creatures easily, power them up don't just turn the enemies into crystal figurines.
I think there should be hard and fast rules on what should kind of creatures can be minions or we are really bordering on Yu-Gi-Oh type madness in D&D. Plus, the idea that non-warriors are able to do what the greatest warriors in the campaign can do is ridiculous IMO. Non warriors, in fiction or even in extremely over the top mythology, haven't been given that kind of power.
Wyrmshadows