[Zenurik popularity vs. the other focus schools. A look at fixing the main problem.]

So, here's the thing: You're in the right area, but fundamentally misunderstood the base issue. 

First thing's first: Popularity does not mean imbalance. Even if you could make a game with mathematical certainty of balance it is very unlikely that every choice would have an equal representation. This is extremely easy to demonstrate - colours. Yes, there are a couple of frames that actually interact with colors in Warframe, but even in games where they don't and are 100% aesthetic (and thus "balanced" by their very nature) the popularity is almost always the same: 1st, usually by a large margin, the deepest, darkest, black; 2nd the brightest, purest, white, and then everything else. Again, even in games where neither color grants any benefit whatsoever the trend tends to exist. The reason is equally simple: different things are different attractive, even if they're equally effective. 

So, right off the bat, just seeing Zenurik (or anything else) top charts of *popularity* is, frankly, irrelevant. Neither is there anything wrong with an option being more popular. If people enjoy a thing let them enjoy it. If there are alternative options for people who don't, why should anyone care? This perception of balance as "equal representation" is a fundamental, "form > function", misunderstanding of statistics.

That said, the reason Zenurik is so much more popular than the rest is, in my opinion, equally simple: a base functionality one. 

Using your warframe's skills is fun, and usually the biggest reason you picked your frame to begin with. Running out of energy and not being able to use your skills is not fun.

Now some warframes, like Inaros or Trinity, already achieve infinite (or functionally infinite for any relevant purpose) energy generation. Zenurik allows everyone else to keep up, and removing or nerfing it just means a great deal of "energy intensive" warframes, like Hydroid, to fall further behind in lieu of these frames which don't need the energy school's regen to keep playing the game at high efficiency.

So the real question is: "is Zenurik breaking the game?", to which I don't think anyone can reasonably say it is. The biggest problem design wise in this game is *peak performance achievable*, it's the reason bosses have been such a cluster#*!%, because buff stacking and weapon modding have gotten to a point where you can spike basically infinite damage in a moment trivialising even astronomical health pools. Zenurik doesn't help with this. Zenurik helps with "sustain", with long term fighting. If anything Zenurik is letting "energy intensive" frames solo the game, something they'd otherwise seriously struggle to do. If anything Zenurik is a *necessity*. 

So Zenurik's popularity is not just "Not a problem", it's actually a crutch that significantly *improves* the game for a large majority of the cast. 

Conversely your "fix" is similarly misguided - splitting the energy regen across two traits won't stop people farming Zenurik, the energy need is still there, it'll just make people farm twice as much! For two different traits instead of one! Which, if anything, emphasises the problem. 

The way to "fix the Zenurik problem", if you choose to perceive it as a problem at all which it isn't necessarily, is to either make Zenurik's energy regen baseline, and retool Zenurik for something else, or give other schools similarly efficient ways to regenerate energy in different manners according to their school's "paradigm".