The rules say (ph p.47):
NPCs only rarely push rolls however - the Referee should save this for the key NPCs in important situations.
Personally I do push skills for NPCs (more than the rules suggest anyway), but that is personally how I play, my comment above was more inline what the rules suggest.
Well in terms of the original poster saying that his players are finding it laughable that they only suffer grazes to the head all the time, I think he should say, "OK, you asked for it" and start pushing NPC rolls a lot more.
In my MYZ and FbL campaigns, I NPC skill rolls, more than the various games suggest I should do, because I want my players to respect combat and to be tactical in combat. I think it is ok because the NPCs, just like the PC, will hurt themselves and/or their gear every now and then by doing so.
edit: also, if you have D D using ROF 2, you have roughly 30% of hitting and roughly 33% of those times it will result in one or more successes.
edit2: for two dice the statistics is: 0 successes 69,44%; 1 success 27,78%; 2 successes 2,78%