First of all, I know the situations in which to use Mind Trap because I play the class (e.g. while in stealth to stop someone from capping a VoidStar door without attacking them). It can be used but it has OBVIOUS limitations. People who play the class and use mind trap know what I am talking about. Also, as Darkness Sin with good utility one of others classes that tends to turn the tide in WZ would be the Vanguard version of the Trooper and its Powertech mirror. I don't play that class, I just know they do a great job of defending and getting objectives. Why do I know this? Because I have played plenty of Warzones against them as a Darkness Sin (its the ONLY class I play) and they tend to cause problems if not ignored. Kind of like a Darkness Sin... Which you would understand if you really played the class (not have a toon, but play the class and spec)

I won't even respond to most of this because your idea of utility is opinion based at this point. However, there are two reasons why I know for sure you haven't played much assassin. 1) Whirlwind? A two second cast time for a stun that can be broken with damage? A Sorcerer with instant cast whirlwind. Yes. An assassin with instant cast whirlwind is dipping pretty deep into the madness tree which kinda mitigates your darkness argument. 2) Mind trap? A CC that can only be used in stealth IF AND ONLY IF the target is not in combat. Tell me how that is viable in the middle a hutball scrum. Not to mention the 50% resolve bar it fills. Assassin CC abilities minus the one stun (shock) and interrupt (spike) is laughable and one of the weaknesses in the class. Don't bring those up to prove your point.

Clearly you have never watched a team Full of Trooper-Vanguards completely dominate a VoidStar...and I'm not talking about the end match stats either.

If you are 31-10 then harnessed darkness is your best friend. It is unique because you can recharge force (over time of course) and heal yourself while doing massive damage. If a sage or shadow isn't getting away from your force lightning with 3 ticks, then they are prolonging the inevitable defeat. Full heal spec sages have to either heal OR DPS. You can heal AND DPS at the same time. Infiltration shadows can only DPS. Same with DPS spec sages (it's important that you keep closing the gap with them as with any ranged nuker). In the end as a darkness assassin, the longer the fight lists versus other light armor classes the bigger advantage you have. That advantage is because of HD and your rotation should always be about stacking the charges. Plus it looks cool to have a purple glow.