The monsters of D&D are designed to stack up against appropriately armed individuals after all, and that does bring an encounter to a screeching halt when the party comes within a spiders breadth of death when the CR 3 critter turns half of them to chop suey in turn 2.
This is a POOR arguement against
magic items. CR3 killing half the party?
I'm going to assume you have 4 characters of 3rd level fighting this thing?
Ogre CR3 with 30 HP and a +8 to hit, 2d8+7 damage... averaging a hit against most 3rd level tanks on a roll of 9 doing 23 points of damage on average will kill the toughest on the team with 2 hits normally. Maybe taking 3 or 4 attacks to do it. The next squishiest may take 2 or 3 attacks to kill, and the bottom 2 take 1 or 2 hits to kill... that is anywhere from 2 (attacking the weakest 2 first, hitting both, with enough damage to kill them immeidately) - 7 (attacking the toughest 2 first, missing half the time, doing average damage) rounds.
what kind of role, exactly, do you expect a 3rd level character's gear to play in this encounter? +1 sword and +1 chainmail? maybe a magic wand? a potion of spiderclimbing?
They don't have the gold resources to "pump up " with magic gear at 3rd level.
If your party is half dead in 2 rounds, something has gone severely wrong.
Does this happen to you often, Iczer?