I don't actually understand the complaints against the 2014 Monk. I think it's the best version of monk I'd seen when it came out.
It has incredibly good, unparalleled magical defenses. Same with mobility. Its at-will damage isn't top tier, but it's respectable. And its short rest based ki means that by 6th or 7th level it has enough to use 1 point per round, and that only gets better. By high level you are always getting that extra attack with Flurry of blows, and stun-locking foes, and being wherever you want on the battlefield, while being really really hard to effect with magic.
My biggest guess as to why people think it isn't good is not following the 2 short rest/day assumption. Like warlock, it is designed to be heavily short rest dependant. It is assumed you are getting your 18-21 rounds of combat/adventuring day, and you have Levelx3 ki to use. If there is a mismatch between that and a group's play style, it isn't because the class is weak. Same goes with warlock. With the right amount of rests they effectively have the same amount of spell slot levels as other full casters, plus all the invocations to compensate for the lack of lots of low level slots for utility purposes.
The other possibility could be just comparing DPR to the absolute best competition, but you can't have top tier DPR and do everything the monk does without being overpowered.
Sure, I think the monk can feel like they can't do much before about level 5 (although the Way of the Open Hand one in our Lost Mine of Phandalin campaign didn't have any problems) so maybe they could have had some features redistributed, but once the game gets going using the default assumptions they are not underperformers.
At the request of a player, for another recent campaign I did import the 2024 rules that make using Patient Defense and Step of the Wind better, not because I think the class needs it, but just because those options never got used since their Flurry of Blows competition was so good, and now they are a situationally useful option.