Why not have a neat luck perk?

Luck seems kind of underpowered, though I may be misreading. Why not add a luck perk? Give it a minimum luck requirement of say eight. Call it "Fortunate son" or something. Once/twice/three times (based on perk level) during an adventure you can reroll a non-combat skill check; you must keep the new roll. If this is dumb tell me.