Ores need to spawn more exposed to cave air blocks, and less when not.

Players need a reason to actually go exploring in these caves. You see, ores arent a reason enough. All a players has to do is stripmine and make a long tunnel and get everything they need, they play it "safe". It's much faster this way but it takes away gameplay, not to mention its cowardly...

To give players a actual reason to try and go through these caves, this is where they find ores the most bountiful and a good reason to explore through it. Of course, it comes with the danger of mobs.

That is good gameplay design, it forces the player to make a decision based off strategy.

Safety, but less ores vs danger but more ores.