As a note about Armour as DR and Defense Bonus - I find they really enhanced the games I was using them in. Players that wanted to play swashbucklers for a long time really could without having crappy AC (high AC is the most swashbucklerish trope in DnD) and guys in full plate totally ignoring little hits was a hell of a lot cooler than just having decent AC.
I've never really used basic shitty mooks as threats, instead as distractions, so it was perfect for my encounter style. But. There are things mooks can do to players that have nothing to do with damage that still screw them over. Tripping them, Grappling them, Bullrushing them (especially into pits - hard to Climb in full plate if you're not heavily invested in it, at level 1-3, especially a surface designed to be hard to climb), smearing them with grease, trying to set them alight... etc. I also ruled (dunno how this works normally) that if you have someone Pinned in a grapple, someone else can coup-de-grace them. Nothing as terrifying for a player as having their full plate fighter held down by four commoners while a fifth advances on him with dagger and stabs it through the eye-slit, even if it doesn't kill them right away.
After I described that scene, he blew through all his action points and bennies against the grapple check from the commoner (other three were using Aid Another), got free, disarmed the commoner with the dagger and rammed it through his eye. Later, he described to another character how terrifying it was being held down like that as they tried to kill him, and actively got better at grappling, to the point that he took Improved Grapple a bit later on. That was a great game.
EDIT: If you make sneak attacks bypass the DR, that makes sneak attacks a lot more powerful. A lot more, at lower levels. Might want to consider whether you want to do that, but mneh.
