Force Bolt is an awesome power indeed.
I've recently made a FF/Energy Defender and planned on skipping it due to redundancy with my primary. In the end I was forced to take it to fill my quota of pre-level 6 powers, and I havent regretted it.
Fast recharge, 100% KB and very high base accuracy keeps the boss of my choice flying through the air. Circling them to keep tossing them back to the melee-ers on the team is one of my favourite minigames.
As the OP said force bolt and detention field can be used to great effectiveness with consideration and wise use between solo and team situations or friends and PuG groups. You will also enjoy the powers that come later in the forcefield set: repulsion bomb, force bubble. They will keep you very active. After 33 months of veteran service, you get the nemesis staff which is much like a force bolt on steroids doing better damage than any mastermind primary attack outside of the pets.
Triumphant Defenders Forever
Psylenz FF/Psi, ArticQuark Storm/Rad, Symon BarSisyphus Bots/psn, Max VanSydow Thugs/Dk, Cyclone Symon Bots/stm, Blue Loki Ice/Cd, Widow 46526
HelinCarnate:OMG it is so terrible. I have the option to take 3 more powers but no additional slots. Boo F'ing hoo.
Thug/FF is a fun combo and was my first level 50 toon. Just bub pets and run into every spawn 
So just a tip, carry Shivans, not needed for most of the game. But needed for AV and EBs w/ high levels of regen. Otherwise you end up with 30 minutes of you and the boss just standing there. (I leveled mine up before I knew about procs, so an -res proc slotted into enforcers will help a lot)
I came back to a character that I had previously abandoned, my thugs/FF mastermind. I quit him because it was a PITA putting shields on all the henchmen every four minutes and his pistol attacks are wimpy.
But now I'm starting to learn some tactics. I respecified out of my pistol attacks. Now I send in the bruiser, order the rest to attack, detention field any serious threats, and I use Force Bolt. I'm knocking down an enemy every two or three seconds and it's fun using Force Bolt. I'm playing solo so there's no one to complain about the knockback.
Plus, I usually only need to bubble the bruiser, and sometimes the Arsonist.
It would be great if detention field was a hold instead of a phase though.
I've found another way to squeeze a little more entertainment out of this game, which I've played for way too long. I hope they release Going Rogue early!