Last game I was running, I had a magically overpowered group. They were all newbs, so most thought that magic characters would be the end all, be all... Heh. So, anyway. Had one Thaumaturgical mage. He lasted all of one session before going back to WoW. Had a social adept, that the player hated after a couple of sessions. He didn't like having to do all the talking. Had a Kick Artist Adept, who has an interesting story for later. There was an Infiltration Adept, going for being a corporate ninja... And the other player actually had a good thought, and went for Hacker. I grumbled about their choices, so I had to make them a meatshield NPC for the first couple of sessions. His job was to get them into the setting easier, and then die tragically.
So, the kick artist, seriously newbie, was supposed to get some intel off of some punk ganger. He decided the quickest way was to beat it out of him. And he wanted it to be a very quick interrogation. So, before checking with anyone else, he told me he was activating critical strike, killing hands, and rolling for attribute boost (strength). My jaw dropped, and I had to ask if he was sure. He replied with a quick "Yep!", and proceeded to smack his adept's hands over the guy's eardrums, trying to cause concussive damage to the eardrums. He rolled the att boost, and maxed his strength. At this point I was dumbfounded, but let him continue in this madness. He then rolled his attack, against a tied-up target... He did rather well, to say the least. After damage was rolled, I explained what happened, and why they would have to find another source for the information they wanted. The hacker gleefully recorded the whole three second interrogation, and called up the ghouls to take care of the body. Suffice to say, they spent the time before their next session actually READING what their powers did...
And yes, I believe in letting the players make horrendous mistakes just to learn from those mistakes.