I like this example.
With a trapdoor, you already know its function. Your roll is to utilise its function.
With the runes, you do not know their function. Your roll is to determine (importantly not to discover) their function.
Now if you are able to determine the function of the runes (via successful roll) you can in theory
Determine that the runes heal the party
Determine that the runes cremove a curse or condition
Determine that the runes provide safe sanctuary to the party
Determine that the runes quench the party's thirst or satiate the party's hunger
Determine that the runes reveal information about xyz
Determine that the runes illuminate the area
Determine that the runes provide resistance vs abc
Determine that the runes provide an escape route
...etc (all via a successful roll ofc)
I think what is helpful is if we could ascertain the limitation, if any, on the players' creativity on the level of power that may be imposed on the runes with a successful roll.
THIS is the benefit the posters above are reflecting on.
EDIT: If we want to equate a trapdoor to the runes we would need to allow a similar level of creativity to the players on determining where the trapdoor opened up to - Sigil, the King's Bed Chamber, Treasure etc.