Thinking on it, one of the biggest problems with current monk is that it does have some really good, really strong features which get disregarded.
If you want to do good DPS you don't go wisdom based, it's the unfortunate truth that Sun and Air stance are strictly better dps but people are hyperfixated on wisdom based monk..
But if you don't go wisdom based you don't meet the DCs for the crowd control and and some of the debuffs monk has to offer- both of which are very good and the debuffs are actually unique in some cases.
A quick and dirty fix I'd probably go with is Henshin has "Your monk attacks now use your highest ability score for their DC" and Ninja Spy would have "Dex or Wisdom"
Shintao is overall an issue of being the handwrap dps tree and the monk 'tank' tree and it does not do a good job at either.
I feel Shintao was just designed originally to give very little DPS as the default monk package gave so much extra damage to handwraps/unarmed and those default bonuses ended up interacting in a very unhealthy way with a later revamp to handwraps to make them into genuine weapons.
That default package got nerfed, the handwraps themselves got nerfed and Shintao never got tuned up to address this.
Whenever there is a discussion about handwraps monk players are very fixated on giving that default damage back but I would argue this is simply the wrong answer.
Handwraps as a category are in fact incredibly powerful, no other melee weapon has full damage modifier on the offhand by default and it has the highest rate of attack of all two weapon fighting animations.
When it comes to monks and handwraps Shintao simply needs damage buffs and monk players need to stop sacrificing DPS by using a stance which offers none and playing focused on a stat with awful metasupport.
Wisdom is honestly the weakest stat in the metagame for everything, the filigree options are inferior, the racial options are overall lacking in comparison. The only wisdom class that excells is druid and that's simply because they're simply overtuned enough even relative to sorcerers and alchemists to offset the difference.
I think there's a few misconceptions in some of what you're talking about in relation to Monk. Before that though, I do agree with you about the Shintao tree not properly supporting either unarmed dps or tanking properly. It has two focuses and manages to do neither of them justice. However I do think there are several incredibly strong options in that tree that any small individual tweak to one of the options will greatly resolve the issue. Namely access to MMR cap for tanks, or access to a better unarmed support.
As for the stance situation I couldn't disagree more about wisdom vs the other stats. Wisdom for the unarmed builds does SO MUCH. With Falconry (yea I know, universal tax but people run inquisitive all the time) unarmed monks get AC, Move DC, and Hit and Damage all from that stat. And of course the only class in meta using wisdom is druid, there's only 3 classes that scale off wisdom in the game. Druid, cleric, and monk (FvS is I think either or, so most go charisma from what I have seen). So yea, the sample size there is kinda low. But wisdom monks have the same benefit for damage which also getting full range on their special attacks. So that is just a wild aspect of monks and it really speaks to the issues with the class as a baseline that people aren't running them in higher reaper content, when they have ranged stun and flesh to stone that BOTH affect reapers. And I think that comes down a lot to survivability. Non-tank monks are just paper thin, and tank monks are not quite up to the standard as other tanks. They work for sure, but there are clear winners and losers. As for the stances, you could literally take the stats off monk stances and they would STILL get used. People aren't using them for the primary attributes, they want the secondary bonuses. And those bonuses work regardless of stat focus. Sun stance generates the most ki and the bonus to tactics addresses any issues with a loss of 2 wisdom. I think the main drag on handwraps is that even with Swords to Plowshares, their crit profile is just subpar, and shintao doesn't deal with imbue at all. Maybe if there was baseline imbue that might be good, but even Sacred Fist is struggling at endgame. So it seems to be that centered handwraps as a dps option isn't viable currently and it's not 100% clear why. There's a lot of little factors at the moment.
For shortsword monks, I just don't see people being all that interested in them. Ninja Spy just doesn't seem to really bring in popularity. Maybe worth a rework but I wouldn't know where to begin. Definitely don't discount the monkcher and thrower builds though. They pack some serious damage and don't care about DCs. I do think that finishers could certainly use some love in the DC category.