The monk takes far too many ability scores to be great at all the things he's supposed to be great at.
Want good defense? You'll need good Dex, Wis and Con.
Want good damage? You'll need good Str (and Dex if you go with weapon finesse).
A Fighter can focus on two ability scores and be awesome: Str and Con.
The fact that a Monk needs to have a good Wisdom score (to get his AC, Stunning Fist DC, Ki and a few class abilities all within the realm of "worth while"), makes for a hard class to build.
The fact that you probably need to focus on Dex to get a decent AC, which means you are likely going to have to give up on something somewhere to remain relevant, and give up some Strength.. and that 2d10 seems so far away, and not quite as big as before.
In PF, Bards, Rogues and Rangers get save or die attack abilities, as well as the Assassin, so the Monk isn't exactly unique in this aspect.
Until the APG and the brass knuckles, it was costly and limited to get weapon enhancements on unarmed strikes. And even with the brass knuckles, it removes some of the benefits of the unarmed strike (it can be sundered, only applies to that weapon and not "any limb/body part", etc).
Having lots of movement is great... until you realize that it is completely out of synch with his combat ability (flurry of blows has more attacks and a higher BAB, but requires a full attack, so no movement during the same round).
A lot of the abilities they get are just to make up for the fact that they aren't using regular equipment. While Pathfinder's Ki points really helped boost versatility, it doesn't really help that the Monk can jump 20 feet vertically at a level where people need flying...
They are certainly better off now than they were in 3.5e... but they are not game wrecking nonsense. Not even the theorycraft supports the overpowered slant, and actual playtesting reveals just how hard it is to pull off the stuff touted in theory.