Wearing a miner's helmet with its candle lit could decrease the ore quality variance of each tile. It may also decrease the likelihood of mining out monsters
I've made a post recently where I found a 64q range in my ore, which imo is too big of a gap. It might be a nice thing if nearby light sources (eg. a lit miner's helmet, torches, etc.) could shrink the quality spread while also creating a cool/sensible roleplay mechanic for the lighting system.