"Not a threat, not a challenge"?
You mean my players don't feel threatened or challenged by encounters where several of them have been reduced to negative hit points? (The only two combat encounters I've run where no one hit negatives, one was ended through diplomacy and the other didn't have any minions).
I suspect that if you are using minions that run away when missed in a lot of fights, it's not the minions that are seriously threatening and challenging the PCs enough to have some of them hit negatives.
You mean that there shouldn't be pets and half-involved bystanders or trainees that are easily driven off while the core of thugs is solid? Or that the Necromancer's skeleton horde should all be almost as tough as the necromancer himself? Rather than a horde - with a dozen or so skeletons, a couple of zombies, and the necromancer in one fight. You mean that I shouldn't run a lynch mob stirred up by agents - but with the would be lynchers breaking when they take a solid blow?
It's not the flavor concept. Your flavor concept of pets and bystanders and trainees and lynch mobs and zombies is totally cool.
It's the game mechanics of minions in 4E. They suck. Additionally, players will go out of their way to waste the purchase of area effect powers or special feats that handle minions in a minions occur in a 3 out of 4 encounter campaign.
Many people house rule change their minions to be something a bit more challenging and less cookie cutter and cardboard, but still have the flavor of minions or mooks.
In my campaign, I have what I call Tough Minions. A Tough Minion might go down in 1 hit, in 2 hits, or in 3 hits. A Tough Minion might run away after getting hit once or twice. It might not. A Tough Minion can become bloodied. A Tough Minion rolls damage so that the players are not in that artificial game mechanics world of "Those are minions, those are not". Knowing which are minions and which are not is playing the mechanics instead of playing the flavor of the game. The pets and bystanders and trainees are the cool elements, not the "Oh, those are minions, let's use different powers on them". That's totally uncool.
It's not the flavor concept of minions and mooks that make 4E minions suck. Minions and mooks are cool from a flavor aspect.
It's the game mechanics. They totally suck if used as is. I'd rather have my PC be dazed than have him fight minions. They're that mechanically dull as written in 4E.
Next week, the 5 PCs are going into Hobbittown and killing a bunch of green grocers for fun. Minions are about this exciting as designed. "Look Jed, I got me a rabbit, yuk yuk, it put up a tough fight, but my dagger won the day". zzzzzzz