About the security level...
It's meant to not be punishing, but sometimes when cleverly used it's meant to be exploited. Getting seen is intended only on the first level, just to teach the player about it. Later it's not required, but should be kept as an option.
"Felt a bit contradictory in terms of game mechanics." because it's not strictly a stealth game. It's more of a puzzle game, as someone mentioned. But that's on me if the player has wrong assumptions.
Thanks!