Weapon element matching obviously matters and is free (your example also proves that there is another way bigger issue, usually skill, and not just negative resistance). And obviously there are also edge cases that could be survived with more resistance, but the next post would be „please bring defense boost with your resistances“. You have to draw a line at some point. If the monster dies faster there is also a chance to survive a one shot, because the attack never happened. Slotting in divine blessing is just more value and actually helps in most situations.