Its also a fallacy to assume everyone screws up on Power Shots 40-60% of the time.
The only time you will regularly get PowerShot to land is if the target is a) a bad b) engaged by 3+ other teammates and can't do anything about your grotesque cast motion or c) is stunned and can't do anything about your grotesque cast motion.
In the case of a), you don't need PowerShot to defeat this enemy. Would rather use RapidShots frankly and get to zero heat for the next enemy. In the case of b) see a). Which leaves c) as the only rational time to use PowerShot. And c) applies only if Unload is on CD. Only if IM hasn't been applied. Only if CGC was applied in the last 2 GCDs. Only if you aren't at close range where you can use Rocket Punch. Only if you don't have the heat availability to use Fusion Missile. And only if no other enemies are nearby and able to interrupt you. This cumulatively happens....not too often.
The big picture consideration here is that there simply isn't a need to use PS because your rotation is full without it. Let's go over some numbers:
IM - used once per 18 seconds, or occupies 1.5 out of every 18 seconds, or 8.33% of your time (actually an underestimate given enemy death and cleanse rates)
TD - once per 15 seconds or 10% of your time.
RapidShots - once per 6 seconds or 25% of your time.
RailShot - approx once every 9 seconds or 16.66% of your time
Unload - 3 out of every 15 seconds, or 20% of your time
ExplosiveDart - once per 15 seconds or 10% of your time
RocketPunch - once every 9 seconds or 16.66% of your time
No rational person would choose to use PowerShot over any of those listed ablities. And those arleady add up to over 100%. Now add in the amount of time you are stunned, relocating, applying stuns, using Jet Boost, FM, etc and it should be clear that any use of PowerShot is displacing a far better use of your abilities. PowerShot - if you are using it in PvP, you are doing it wrong.