How come no one researches Hi-Sec Auto Tracking?

Solution 1:

Generally-speaking, neither Hi-Sec Auto Tracking nor turret spam are the best reactions to mutas. Throwing a turret or two on your mineral line works if you expect continued aerial harassment, but the reaction most pro players have to an opponent going mass muta would be to create a unit-based counter.

Turrets and your other defensive structures aren't mobile. Because of that, they cannot win the game for you. They only keep you from losing. By investing in units that can get rid of mutas, you're investing in something that can also be used to win the game. Overall, that tends to be a better use of your resources.

Solution 2:

It's not true that no one researches Hi-Sec Auto Tracking; the caster "TotalBiscuit" is an advocate of that upgrade.

(That said, you can find the streams of his games by searching for "I Suck at Starcraft Live", so take that for what it's worth.)

I usually research it too, fairly early; I find it especially useful when you have Planetary Fortresses; just the increase of 1 in range actually increases the total area of effect like about 35% or so.