How is using encounter powers, stances and movement = little/no effort? Clearly, that party is taking the obstacle that is the minion horde seriously, choosing powers and taking actions to eliminate them before they become a problem.
If your minions are sucking up actions and getting in the way of movement, then they are doing their jobs. They do not need to do damage or survive even one round for this. Just obstructing a charge lane for a turn or getting in the way of a warlock's curse is plenty. If the party is intelligent enough to deal with this obstacle, using powers, movement, actions and such, then good on them! Their DM should step up to the challenge instead of looking for the nerf bat.
You are missing the point completely.
The minion rules are bad from the player's POV, not the DM's.
It is BORING to drop a Cloud of Daggers on a minion:
DM: "What are you doing?"
Player: "Well, I drop a Cloud of Daggers on the minion flanking the Fighter because I
know it will kill it."
Yawn. As opposed to doing some other action. The PC does not know it will kill the minion, the player does.
This is also similar to 3.5 Clerical healing. The 3.5 Cleric was expected to use up a standard action to heal, so he did. The 4E Wizard is expected to use up a standard action to auto-kill, so he does.
That's not fun. The reason it is not fun is because it is not a challenge.
The minion rules allow for auto-kill with certain powers and auto-kill is boring.
The fact that minions are paper tigers is bad enough (that too is boring for some players, like cats, some players like to toy with their enemies, not have them fall over when the PC sneezes). The fact that some powers auto-kill minions makes it worse.
And, the convenience for the DM outweighs the fun of the players. The implementation of the minion rules are all about DM convenience, not about monster obstacles. Sure, they are monster obstacles, but that is not why they have one hit point. The main reason they have one hit point is so that the DM can more easily use them (they had more hit points in early 4E design and it was changed to one for DM convenience).
Sorry, but that's lame. That makes for an inferior game mechanic when the DM convenience rules force certain player game decisions.
And, a PC using attacks that do half damage on a miss do NO damage to a minion. That too is a lame rule (added on top of the first lame rule, a snowball effect). The player went out of his way to use up a powerful attack that is sure to damage, except because of the inferior minion rules, it doesn't. If you consider that FUN for the player, you have a strange idea of fun.
Bottom line: The concept of minions is great. It's great to have fodder enemies. The implementation sucks.