I can agree that Stunning Strike was bad design, for sure.

It's interesting when you compare the Monk to casters, who typically also have incap abilities that cost a resource. While I don't think casters are designed perfectly either, a caster isn't useless if they can't use their incap spell on an enemy (through immunity or high saves or whatever) whereas a Monk that can't stun is doing really nothing but subpar damage. Casters usually spend more of their resources on an incap spell, and they sure aren't spamming it three times per round. Hypnotic pattern can still cause ridiculous swinginess when it comes to balancing fights of course, so maybe it's not the best benchmark anyway.

With that in mind, I think Stunning Strike should probably be less spammy (which is the main part of what they did) but obviously it needs to be made up for by making the rest of the Monk much better, which I don't feel was really achieved here.