the balance could be easily achieved using simple things like range, damage, rate of fire, area of effect, armor rating, and armor penetration
True dat.
I still usually ignore hull types and bonus types.
On what difficulty level? Do you always play the Fallen Spire campaign?
I usually play 9.6-10, depending on whether or not I want to win, and almost never play Fallen Spire. It's fun, but there's so much else in the normal game to do.
Now, it got trimmed, but there are some hull types and bonuses I do care about.
Anti-Heavy Bonuses are important for dealing with Carriers, and other major threats. This means things like Laser Turrets are high priority.
Anti-Command-Grade is important, with only two fleetship sources, especially when H/Ks are expected to show up. So Bombers it is, barring random chance.
But composite? Close-combat? These hull types don't belong to many major-danger units, so they don't need to be countered. By the same logic, there's no real use in pushing to get units with those hulls.
Medium hull is good to counter, because it is so popular, but that's just strategic efficiency, not tactical significance.
Scout and Polycrystal hulls are useful against certain AI fortifications.
But, in general, most hull types have 6-8 units of that type, and most have 15-20 units with bonuses against them - averaging a 3.0 multiplier.
So, generally, except for major threats, you'll expect 25-33% of your fleet to have a 3x multiplier against each hull type the AI fields. When you have 6+ unit types, and the AI is fielding 10 or more - it all averages out.
Finally, when I'm stretched for resources, I'm more likely to look up the specific counters for incoming waves... but I'm almost as likely to say "Build MORE UNITS!" as "build more efficient units". Or, "WARHEADS!", actually.
So, again - I care a lot about Heavy and Command-Grade. Specific circumstances call for more efficient use of units... but usually, it doesn't make that much of a difference.