Exactly what sort of flavour is a Kineticist supposed to have beyond just someone who uses psycho-kinetic powers? The argument for Wu Jen is clearly in favour for the fluff associated with them.
Well, it doesn't need to be called a "Kineticist", it could be an "Elementalist", or some new name that doesn't already have a history of already being in the game and is applied to something different than what's being proposed.
Really, the elemental aspect of the original Wu Jen class is very minimal—if you learned all of the spells (of the levels you're capable of casting) of a certain element*, your spells of that element were harder to save against and did more damage. You lost your "mastery" the next time you gained a new spell level to cast. Depending on how well or how poorly you rolled to learn new spells (because that wasn't a given in 1e unless your DM was lax), and the availability of finding new spells, you could be a "master" of all five elements, or never master a single one.
*Chinese five elements (Wu Xing), specifically.
About the only archetype I can think of for a Kineticist is one that a young Drew Barrymore once depicted more than 30 years ago.
The "benders" from Avatar: the Last Air Bender are perfect examples of kineticists. Sure, there's that Way of Four Elements Monk, but I hear no one ever plays that.
And yes Wu Jen or Wu Ren (using modern Pinyin spelling) is very much a D&Dism. You know what the suggested Chinese name for a Wizard was back in 3e? It was Wu, which happens to be the same word in Wu Jen/Ren, just without the word "Person".
A "Wu" from Chinese tradition is more of a shaman type of character—communicating with/placating/exorcising spirits than a D&D wizard.
The D&Dism that is the Wu Jen, really doesn't need to be updated at all—choose wizard, and you're pretty good. But give us those cool Wu Jen spells from OA. But if they insist on using the term Wu Jen, it should have more continuity to the original class (and being a Wizard subclass would be the best fit).
And, BTW, I really wish D&D would modernize to the Pinyin transliterations for Chinese words, but that's just me.