I think a simple fix could be:

Super Amazing Really Really Good Targeting Computer

Modification

After you declare an attack using a [Torpedo] or a [Missile] secondary weapon, before rolling attack dice you may immediately perform a free Target Lock or Focus action.

The point being you have to get your prerequisite token before you can declare the attack, and it's then spent, so the effort to set up the shot is still there, but then you get another token which you can use in this attack or keep for later. Unlike some similar ideas, this one doesn't take Homing Missile's advantage away.

You could potentially make it "before modifying attack dice", but in that case it would need a substantial cost as it'd be quite kick-arse.

Thanks for the comments so far.

I am going to prox a few games with the OP fix with Rebels and with Imperials. Hell, maybe even with Scum.

The two primary disadvantages to Torpedoes and Missiles is the limited number of times they can be used which lead to them being an inegfecient expenditure of points and the fact that you must spend a Target Lock or a Focus in order to fire them making it hard to boost your rolls for the attack which compounds the first problem by ensuring the attack will likely be mediocre and ensure that the points were wasted.

I think Extra Munitions opens up a lot of options for future improvements. With the introduction of Munitions tokens we might see more upgrades come out in the future that expand upon them. This gives FFG an open option for tweaking the costs of munitions on different ships as they go. They can either add more cards involving these tokens to add more shots to a ship or possibly add cards which manipulate the cost of munitions upgrades attached directly. So that settles the cost/limited use issue.

As for the limited roll boosting... We have Deadeye... But that really just trades one valuable boost for another and in either case still leaves you trying to perform a second action just to get one bonus to your roll. It is also difficult because some of the ships that specialize in ordinance, most notably Y-wings, are lacking in EPT slots which makes it even harder for them to get the second action.

There are a few cards which help with this, but too few:

Horton's ability is almost as good as a TL. I say almost because it is limited to only rerolling blank results. If you don't have a Focus to spend with it then it is not as good as a normal TL. Though if you can get the Focus to spend along side it then it is as good as any other Focus+TL combo.

APTs allow you to change up to 3 blank results to Focus results. If you manage to have a Focus token handy then statistically speaking if you don't end up with 5 hits afer your Focus is spent then the dice gods have forsaken you.

R4 Aggromech can work along side Deadeye on Kavil. This way you get to spend a TL to boost your attack at least.

Drea gets to acquire another TL after spending one at the cost of a Stress so you can acquire a TL, spend your TL to initiate the attack, acquire a second TL and a Stress, and spend the TL to boost your roll.

I am sure I missed some, but you get the idea...

We could use more.