Force Fields is an interesting set to me. My first level 50 was a Mercs/Force Fields Mastermind. One thing that stuck out to me and that probably sticks out to a lot of people as well is how many powers in Force Fields you can get away with skipping. I feel like most people go with Deflection Field, Insulation Field, Dispersion Bubble, Personal Force Field, Force Bubble and Force Bolt (usually because they have to). Everything else from there I think doesn't suit most people's playstyles or mesh well with how other people play the game (knockback is definitely frowned upon these days).
Now Force Fields is a very foundational set. Sonic Resonance, and to a lesser extent Cold Domination, Thermal Radiation and even Traps, all build off the house Force Fields built. Sonic Resonance in particular is the most one to one in terms of influence, it even has a foe capture power! Ultimately however these sets have very different cores and are more well rounded than Force Fields, showing the developers had gained a much greater understanding of their own game systems and player's desires.
I don't see Force Fields run much these days. I think the fact that it was made with an older paradigm of gameplay might be the reason for it but I don't necessarily see anything "wrong" with the set. Its focused around defense buffs and knockdown/knockback and that's exactly what it delivers on. It's also a very conceptually compelling set that features prominently as a power in comic books. However I do wonder, especially considering how powerset design has evolved through the game's history, what Force Fields would look like if it were made now instead of at the game's opening.
So, let's say you had an opportunity to reimagine Force Fields: Would you still create a set centered around defense buffs and knockback/knockdown with only marginal or no changes? Or would you turn the set on its head with a totally new vision of its concept?