I think that is a throwback to each edition constantly trying to emulate historical oddities from early editions where it was a hybrid of fighter & thief tables that occasionally picked up messy bits that then became central to it by pure chance & how the next edition worked. This video goes into the history of monk through editions.Good points. Admittedly I didn't run the math, but I just wish the Monk wasn't so inherently MAD and could have a little leeway in terms of ability scores to make different flavours of Monk easier to build.
In every version so far monk has been an awful mess that might progress to kind broken & disruptive when it suddenly starts stomping on people's niches after many levels of gm's making one off exceptions for poor bob the monk stuck playing bruce lee. Others have suggested splitting it into two forks but I suggest going one step further & jettisoning the baggage in favor of something that fits from the ground up using inspiration from modern sources like anime. Ignoring the overpowered main character syndrome almost always present in anime here are very few characters that look much like d&d's monk but plenty for the other classes look similar... with the exception of lee from naruto who is described as such "During his time in the Academy, Lee proved to have no talent for ninjutsu and genjutsu(the stuff literally everyone else did). When he was mocked by his peers because of this, Lee persevered, focusing on taijutsu. After he succeeded in graduating he was added to Team Guy along with Neji Hyūga and Tenten. During the team's first meeting, Lee vowed to become a powerful ninja without using ninjutsu or genjutsu. Neji laughed at him, but their sensei, Might Guy, took a special interest in Lee. He encouraged Lee to keep at it and, in time, began teaching him powerful forms of taijutsu".
nearly every time he was on screen through the series it was a disruption & so much of the monk's "just like everyone else but better because it's skill not magic or wood & metal" is not much better in most campaigns. Examples of fictional eastern equivalents to European fictional heroes like merlin robinhood & so on are so much more available these days with the state of internet streaming moving so much of it from torrented fansubs & hard to get expensive vhs/dvd sets to being available on mainstream media consumption for many including some broadcast/cabletv airings. How about monk fit the system where basically every setting has extensive & well known magic use in place instead of trying to replicate the fact that david carradine played a stranger in a strange but totally mundane land in the early 70s on kung fu?