It's pretty clear that the masteries are meant to serve specific roles. The fact that certain masteries lose 1v1's is by design; they make up for it in other ways. Looking at the game's design philosophy, the purpose is to re-enforce the idea that choice matters. So when we talk about balance in Nin, as much as we want to talk about 1v1's, we really have to ask whether there was a meaningful choice to be made. Anything that's blatantly better across the board is not a choice as far as players are concerned. I agree that access to instant CC is one of those things.
Tai users arguably sacrifice most of their team-fight usefulness to dominate 1v1's with instant CC and interrupts. The same is not true for 20 Str Fan or Pipe users, nor the new triple-stun Fans. It's also not true for Medics, which combo well with any mastery with little-to-no investment purely because of P Scalpel. The answer isn't to remove all instant CC, or homogenize the Masteries by giving it to everyone. Instead we should be more cautious about doling out access to the mechanic.
Interrupts are part of what helps to set the hectic pace of combat in Nin. Without it, especially in this Tank Meta, it would slow down to a crawl of exchanging 1-2 cast-times. Interrupts serve a purpose without being overpowering by setting up unavoidable combos. Silences and soft CC are the way forward. 20 Str Fans should interrupt, but not knock-back, higher Str fans can do a more powerful knock-back instead of stun. 20 Str Pipes should slow instead of snare, higher strength pipes can do what they do now. P Scalpel can silence and poison, which together is more than enough utility.
The specifics are less relevant, but the point is no one should have access to such strong mechanics with no real trade-off.