To use up a standard action or three in an encounter or allows PCs to be rewarded for their ability/equipment/class choices.
Unfortunately, minions do have an XP value so there _is_ a balance metric for how much effort they should take to kill, and many of the things I mentioned do not take standard actions.
Now, that does bring up one other option - drastically decrease the XP cost of minions as you move up in tier. Unfortunately, that favors ranged minions far more than melee minions and can lead to unbalanced situations where certain groups are still _far_ better at killing minions with automatic damage than some who aren't. Oops.
That requires just enough actions on the part of the PCs to give the encounter a few more points of challenge while at the same time making things more interesting.
Indeed - the problem becomes when they don't require those actions or increase the challenge sufficiently in the face of certain tactics.
For example, let's take Tempest Whetstones which are mostly fine _except_ when you consider minions. They're a minor to apply, last the entire encounter, and are effectively free starting in Paragon and Epic tier. They deal 2 damage to all targets within 2 squares of any creature you hit automatically.
So a twin strike archer ranger can be killing all minions with 2 squares of any other target, automatically. Similarly, the cursing warlock can use a +1 rod of reaving in his off hand (again, effectively free in Paragon tier) to kill all minions he curses, and two-fold curse means he can potentially kill two minions every turn. He can even do this while still blasting a different cursed target. If he's a feytouched warlock, with slashing wake he can also be killing every adjacent minion when he curses any minion as a free action.
These abilities I'm mentioning weren't designed to kill minions - they were designed to add cool effects and extra damage to characters, but they unintentionally _destroy_ minions. In fact, in the original minion rules we saw at DDXP, it required a hit to kill a minion (they were immune to auto damage), so it may well be that they were _really_ not designed with automatic damage in mind at all since all of these items and abilities were at least drafted by DDXP.
In the end, I think my final statement (albeit slightly revised) still holds true. To each his own. If you feel modifying the rules for minions will benefit your game then by all means. My intention in replying is simply to restate the fact that some PCs may not appreciate the change, and in the end we all DM for the players enjoyment.
Exactly - that's why I was suggesting not to just make it a pure nerf. My players genuinely dislike that minions are immune to half miss abilities, and some think it's cheap that automatic damage just kills them. I agree, so my proposal works for my game since I think tracking bloodied is easier than tracking temp hp or rolling saves. For others, not so much. Oh well.