Utility of level 3 sensors?

Solution 1:

Level 3 sensors have a non-combat benefit, since having them will present additional blue options in some encounters.

Another benefit of seeing their systems is that you can see the cooldown on their cloak (if they have it), which can help you make decisions when firing weapons or teleporting crew in.

Solution 2:

Another benefit could be in the, admittedly very specific, scenario where you have a basic Ion Blast (Mk I), no other ion weaponry, and not enough power to power all your ship's systems (for example, your power is already maxed out powering different systems).

It can be useful to know whether your opponent has an even or odd amount of shield power. If it's even, then firing the Ion Blast will take away a shield bubble. If it's odd, the Ion Blast won't do much.

Enemy ships can have anywhere from 2 up to 10 power in their shield system, so only when they have 5 shields do you know for sure how much power is in that system.

Solution 3:

The order that the weapons go down is related to the charge. You can use the sensors to decide when to hit the weapons in order to take less damage.