Whether you liked TK or not is a matter of taste I suppose. What I mean by saying that it worked, is that it's accomplished several things:
- Adding an interaction with MNK's core mechanic - GS - which capitalized on its unique quality of being a buff that has to be build up with stacks.
- Added more synergy between several skills in the job's kit(TK, PB, Coeurl gcds, Wind Tackle, IR and RoF).
- Made a pretty niche skill(TK) a regular part of MNK's rotation.
- Made up a significant portion of the job's dps.
- It also did not really affect the GS maintenance mechanic during downtime/disengagements, so it could work perfectly well alongside current Form Shift and SSS.
Basically, it was not just something they tacked on that turned out to just be some niche skill that sees use only a couple times per fight. Which is insanely ironic, as they didn't even add it on purpose.
As for GS not being designed as a resource to be spent - TK rotation was not SE's design either. The point is that just because something was not originally designed for a certain purpose, does not mean that it should never evolve for it if there's potential to make it work.
The one clear issue with TK was the need to weave 4 skills just to get a single GS stack from RoW, which was obviously a result of it being unintended and could be easily fixed by tying that GS stack to a dedicated ability instead of the fist mechanics SE so illogically clings to.
I don't like the idea of making TK another Xenoglossy for 2 reasons: one is obviously that it's kind of lame to just grab a mechanic from BLM and slap it on MNK, other is that it doesn't interact in any way with what makes GS unique - which is the stack building. Neither does adding a skill which instantly grants you full stacks, as then you just make GS a "single button application" buff like anything else.
MCH rework might've been well received, but it is a good example of one that's been so radical, that it might've as well been a new job honestly. Not a single mechanic from HW/SB MCH has been kept intact - heck, even aesthetics have mostly been changed - and I think that's a terrible direction to take with any job, unless there's really nothing enjoyable about it at all.
That and also I think it's been reduced to something utterly dull, but that part's obviously subjective given its popularity.