I play on Roll20, where it is very easy to automate many parts of game play. As the DM, I frequently need to make hidden perception checks for characters. I currently use Passive Perception, since that is what it is for. However, Roll20 makes it very simple for me to roll perception checks for an entire party. The idea of a randomized outcome has great appeal to me, since it allows the low Wis barbarian to occasionally notice something the others don't, or the high Wis cleric to miss something because he is preoccupied.
An automated group check allows that. Off the bat, I don't see any major game imbalance by actually rolling a secret check rather than using static Passive Perception. Am I missing something, though?
Is there some significant game feature that is changed or lost by rolling secret perception rolls rather than using passive perception?