I do understand minions and I understand them as being representative of 4e's extremely gamist approach to design. IMC the word does exist outside my PCs and a terrible 15th level demon capable of ravaging an entire town in a narrative sense will not be turning into a 1hp soap bubble once the PCs arrive to save the day. If you want your PC to be a real badass, kill some critters with actual HPs not mobs of drones designed to make your PC look good. The whole minion thing smacks of a cheap setup to make people look, mechanically and narratively, more potent than they actually are.
I agree.
I'm not opposed the idea of easy-to-kill mooks, but I think they should be used sparingly--as the cannon fodder in a large scale battle, or as the guards patrolling around the wall of a compound the characters have to infiltrate--that sort of thing.
As for the 1 hp, I understand the abstraction, and I understand the goal, but I don't like the execution. Its just part and parcel with the whole "black box" design philosophy, and it leads to all the odd situations that others have mentioned. Hp should mean something whether the characters are in the room or not, or they mean nothing.
In which case, I guess not giving minions any hp, and just declaring them "one-hit kills" would actually make more sense to me. But I still can't wrap my head around a wizard with a dagger killing a demon with one hit.
Ultimately, I think the 1 hp minion takes too much out of the character's hands. The kill has nothing to do with the character's skills, and everything to do with the what the DM wants, and the minion's metagame characteristics. To put the power back in the character's hands, I would give minions normal hp, but give the characters a x10 or x20 multiplier to damage when they hit it. That way, you avoid all the weird "a demon is fighting a rat" corner cases, hp actually means something in the game-world, and characters still get to wade through foes like a scythe through wheat.