If you never use Gunner, then you are likely getting really lucky roll matchups, or you are playing against mostly (only?) low-agility targets, or your opponents aren't using focus/evade enough.

For example, if you are firing against an Interceptor with Push The Limit, they can often have both a focus and an evade. They are rolling a minimum of 3 green dice, sometimes 4, 5 or even 6. If you have to take a shot at one of these, you will likely miss the first one, but hopefully make them spend their focus/evade tokens, leaving you with an advantageous roll with the gunner.

Now, if you are playing a mirror match versus Rebel ships with only 1 or 2 agility, then yes, Gunner ends up being a waste of points that you could have put to better use most likely. Against TIE lists, or in a tournament, Gunner is one of the best cards in the game.

How do you get 6 green dice?

3 base, 4 - at Range 3, 5 - Range 3 through asteroid, 6 - Range 3 through asteroid with SFG

Now, i figure if one ship would get the 6 dice, there should hopefully be a different target rolling far fewer dice.

Now, i figure if one ship would get the 6 dice, there should hopefully be a different target rolling far fewer dice.

Agreed, which is why I said, "if you have to take a shot at one of these."

3 base, 4 - at Range 3, 5 - Range 3 through asteroid, 6 - Range 3 through asteroid with SFG

You are right, but sometimes it is easier to write it out like this:

3 Base

1 for range 3

1 for obstacle

1 for stealth device

I also put down dice on the table too since it can help visualize it.

The nice thing about Gunner is that it will let you shoot at a different target with Han. This means that Han CAN "safetly" try to shoot a Stealthed Soontir who's hiding at range with a shot and reroll and if it fails gunner would let him pick another target or take a second shot at Soontir who may have given up Focus and Evade the first time so he could keep his Stealth Device. With Gunner onboard Han can afford to attempt those risky shots far better than someone else who needs to maximize his potential output against TIEs.