Just dropping by to say that I really like a lot of your suggestions, Philotic - they keep in line with how I myself have played the power-set while also adding some quality of life improvements that enhance them further.
I'll admit that while some suggestions such as an absorb mechanic do sound nice, they certainly aren't necessary for Force Field to function; reading your guide to Force Fields, and indeed, playing through the game, it does feel like the power-set is a balance of defense granting abilities, control, and enemy positional manipulation.
Your suggestions all seem focused on making Force Field better at those things, which I appreciate, and agree with a lot. With that said, here's my own thoughts on the improvements you've laid down, on what I myself would like (everything else I haven't mentioned I'd approve of, basically):
Detention Field: Having a guaranteed way of taking an enemy out of the fight is a potent ability, if a conditional one, makes it fill a niche that a regular hold doesn't (which I very much appreciate). Duration can indeed be problematic in groups, though the fact that ideal targets for the power tend to be resistant to status effects, and thus have them last a shorter period of time, potentially mitigates this.
Reducing the duration + recharge of the power does make sense. A toggle might be a nice option as well, or even just a way to cancel a currently present Detention Field. Having a high enough magnitude to completely deny an AV action at all sounds very fun: seal them off for later, deal with their lackeys in the meantime, before engaging. Still needs to be used judiciously, but can now be applied in more situations that could potentially benefit from it.
In summary:
Higher magnitude (even AVs?)
Means of cancelling early/re-implement as toggle
Lower recharge/duration?
Do the same for Sonic Cage of course!
Force Bubble: This power, to paraphrase your statements on it, acts as an absolute positional power, moving enemies across the battlefield. As such, I think that your potential improvements on it are one piece of the puzzle. In its current state, Force Bubble is quite useful as a general keepaway power - it's a great way of herding mobs into corners and the like, with a large enough radius to keep them in place without too much worry. However, I very much like the idea of having a smaller version that has a stronger repel/you shall not pass effect.
So I think combining these two powers into two different 'modes' might be quite interesting, allowing a character to switch between each effect when needed, perhaps in the form of a popup temporary power. Additionally, an even wider range, weaker repel effect might be quite interesting. It'd stop minions/lieutenants getting close (to the point of not being able to use ranged attacks), but let stronger enemies bypass them - a 'you shall not pass' of a different kind. Kind of like an inverse of Detention Field, that you're cordoning off minions and lieutenants for later, to focus on the main, stronger threats.
In summary:
Switchable modes to change the way that Force Bubble works dynamically
Regular Force Bubble = same radius, same magnitude
Focused Force Bubble = smaller radius, higher magnitude, slow to prevent faster enemies pushing through?
Diffuse Force Bubble = larger radius (out of range of most ranged attacks), lower magnitude (bosses and up can pass through)
Thought it might be nice to put down my thoughts on them both - definitely love a lot of those improvements you've proposed, Philotic! The caveat here though is the fact that I play the powerset on Controllers; my experiences, and thus viewpoint on the set likely vary somewhat as a result. Hope these opinions garner some discussion!