The Gnashing fang comparison is a QOL fix and thus retains the feel of the Job, I'm looking to those kinds of solutions that preserve a "if it's not broke don't fix it" as the feel of the job in 6.0 was very excellent especially after the media tour feedback being implemented so quickly.

Regarding Seigan there might be a technical limitation to it, regarding something I heard Yoshi P reference in one of his interviews for the media tour (either Drak Gamestein or Woops I can't remember on youtube) and it was the concept of "animation data" which essentially amounted to abilities being removed as their animations imposed a technical limitation on the game due to trying to trim file sizes, or some other stuff it wasn't really elaborated on.
(servers possibly, just really technical stuff as all data is valuable in optimizing an mmo)
Seigan has a unique animation, but the current iteration of Third Eye just granting kenki saves on animation data instead of allotting it to Seigan and that other one that heals. (thus optimizing the technical limitations of the game)
I can get why Seigan may never come back in it's former due to that.

And in regards to Kenki, it was something that I floated around 50 before spending on excess Shintens, as I needed to make sure that I had enough for Kaiten. (this was some level of management needed to make sure you played properly)
This was also nice because it meant I had to manage / track the two resources in relation to each other. Now that Kaiten is gone, Kenki has no interactions whatsoever with Sen, so just focusing my attention on Sen and only pressing Kenki when it glows simplifies it.

If they increased costs it would just lower APM (thus slowing down the job), and our APM is quite nice as it is right now, I would even enjoy more APM sometimes as a former SHB summoner.
To keep kenki relevant they need to have us think about it, but not be stressed out by it rapidly approaching and needing to be culled constantly. It needs to interact with the other half of our kit, like kaiten bridged the gap with Sen / Kenki, not just be ANOTHER resource which is the issue on jobs like Scholar, which could really do with a complete rework around it's faerie gauge.

So yeah as it is currently we're not doing anything with Kenki, our incentive to pool it was weakened with Trick Attacks buff being passed onto the 2m Mug Window, so there isn't a 1m window we pool for (the only window we don't get 1/2 our kenki for free).
The simplest course of action that doesn't result in any real tangible loss is to just simply use shinten ASAP IE when it glows. You can cut out any and all thought regarding how much kenki you have, and focus elsewhere, as long as Shinten is glowing you're fine.
So the kenki bar is just a distraction, IE UI bloat, and this can only really be changed by making us change our thought process around what to do with kenki, not so much speed up the process, or make it as restrictive as soul arrow (an 80 out of 100 spender on bard, that's just really annoying when you have a tight rotation going on).