Moniker said:
It is entirely ridiculous to assume that a missed burst or blast that does half damage would not kill a minion.
I can already see that I'm going to have to houserule this, until WotC can provide any better reason NOT to.
I'd say it is because then minions become very little threat to a party that has access to "damage on miss" effects. We already know that the fighter has access to at least one of these, to say nothing of the casters such as wizard and cleric. It's at least somewhat safe to assume that most if not all classes will get "damage on miss" effects at some point in their powers. It's your game, but if you houserule that minions die from missed half damage attacks, players that use their half damage attacks often, will kill minions regardless of what their attack roll is.
To illustrate using an extreme example (and yes, I realize that extreme examples are often inaccurate, but I'm simply using it because it best illustrates my example) a level 1 character with a half damage on miss attack could kill a level 30 minion without having to roll to hit. By comparison, if the minion is immune to the half damage miss, the same level 1 character will need a nat 20 to kill it.
There's nothing to say that the minions aren't damaged by such attacks (scorched by a fireball or a flesh wound from a sword), they just aren't killed by the attack and MECHANICALLY haven't been harmed.
In response to the barfight question, I'd narrate that the minions are able to trade a few punches with each other, but get knocked out cold if a PC (or non-minion NPC) hits them. If a minion is dominated by a PC and attacks another minion, hitting him, he knocks the guy out. If minions on two sides of a battlefield exchange volleys of arrow fire, a lot of them are going to die (assuming that they can hit each other). IMO.