the issue would be immersion.
unless its something stuck on your back, carrying a torch would require you to give up a weapon slot, and would directly punish 2 handers as they wont be able to use their weapons.
i like the look of pestilence imbued items and i really hate how other elements simply light up the room and feel punished for not using a different element.
illuminating via spell is still optimal as the lighting is not limited to a small patch that your weapon provides. its also constant so its not headache inducing.
to me the REAL solution would be to REMOVE dark areas entirely but make it similar to the potion vendors quest where pathways are hidden unless you trigger something.
also, a quest could be created for the player to gain the ability to “see” the hidden spots permanently.
i can tell you with 100% certainty. the “me” of 20 years ago would have used illuminate in EVERY single area to look for secrets. this is because of the description given on the rune. instead of being a bonus, it can be crippling towards people with OCD. i used to want to do such things but now im older. i play games to kill time. i enjoy organically hidden secrets where you may stumble upon a hidden switch or walk past some bushes to find secrets off the main path. having to manually cast a spell to get “secret revealing vision” reminds me of my time playing dragonage inquisitor. theres a scan button to reveal all interactables. when i played the game, every few steps i would hit the button as tho i m a bat relying or whale relying heavily on sonar.