What is kind of funny is the "entrenched" pvp crowd recognized controller holds were so powerful that they were literally banworthy across 8 v 8 matches even down to around 5 v 5's. Not being able to move for 3-6 seconds when a player can die in less than 1 second (or even a single server tic) meant that holds were a death sentence with their base 4 second duration.
However, this increased viability came at the cost of their 1 v 1 prowess. Builds like Ill/Storm, Ice/Rad, Fire/Rad, etc no longer really worked in 1 v 1's because 1 v 1 matches vs. hard CC AT's no longer became "how fast can I run my opponent out of BF's so they simply can't play their character the rest of the match". While this was a positive change, the 1 v 1 system overall is still pretty out of sorts and with so many sets, power combinations, and IO's / builds / etc whether it was the i12 system or the i13 one it'd still be pretty broken and monumental to balance.
When clear mind and equivalents started to give mez protection again, they were unbanned and you regularly see at least two controllers (grav or Ill/emps or pains) and sometimes you'll see a niche debuffer Ill/rad or Ill/psn run. So as far as "controllers becoming powerful again" they are to the point where the the portion of the community who plays this game as a team game actually came together to soft ban 4second + holds. They might not be the way that you want them to be, but they still have their purpose in PvP.
While it'd might be great if every AT and every powerset was viable in 1 v 1, 2 v 2, 4 v 4 up to 8 v 8 matches I think realistically you (and pretty much anyone else) would have to accept that some things are going to be better at certain facets of PvP just by the sheer variety of things that exists.