Threads like these... they anger me. They anger me because they're chock full of people who... and I'll try to be as subtle about this as possible... but people who DON'T HAVE A CLUE WHAT THEY'RE TALKING ABOUT.
And what are they talking about? Sure as




not dungeons and dragons.
You know who "optimizes"? Players. Almost universally it's players. A DM that "optimizes" can simply say "rocks fall, everyone dies" and he "wins".
So far as I know though, D&D is a "co-op" game. It would be extremely rare for a player monk to up and attack a player wizard. In such an instance it would be the MONK strangely enough, that would have the benefit.
Why? Because unlike the strange "I'll cast all my spells and get prepped and then you run over and try to hit me" nonsense it comes down to one of two things. Either the wizard and the monk are standing next to each other in a 'discussion' that results in the desire to murder one another or one decides to actually kill the other guy and bides his time and strikes. A wizard snoozing while the monk agrees to keep watch and then the monk up and slays said wizard via... whatever. Which is probably what a monk that wanted to kill the wizard would do. He certainly wouldn't be stupid enough to go toe to toe with someone who can bend space and time at a whim. If the wizard tried the same tactic the monk at least has a few natural defenses in such an event. Tipping the scales slightly in their favor.
But none of this is here nor there.
When the Monk is "caster killing" he's not targeting an OPTIMIZED PLAYER CHARACTER... he's targeting the generic caster the DM has rolled up. As Tucker's Kobolds illustrates the DM can rape about any party they elect to relatively easily, Wizard or not. The DM wins. Consequently the DM rarely ever needs to optimize.
So, take a good hard look at the tools your player character monk has and they are excellent against many generic spellcasting NPCs.
Feh.
And that is what the monk is balanced against. Not wizards. Not clerics. Not even fighters. They are balanced against their niche in the game.
What's with people trying to turn D&D into Wow? Christ. If you desperately crave pee Ved pee that bad go play a game developed with it in mind and stop trying to use it as some warped metric to determine the validity of a character class.