There is a lot of choices for these now but why does no one use them. For example how many were used in Regional's/National's, which is the test to see if anything is competitive.
Possibly the main reason for them not being used is that they are only one shot. A HLC has 4 non initial crit attack at range 2-3 for the whole game at 7 points. Whereas proton torps are only one shot spending a TL to fire same amount of attack dice(better chance of at least one crit) costing 4. How many times would someone fire a secondary weapon turret in a game?