Why do we say the Monk is a frontline melee guy? What do his class features say? Everything the Monk has is for that role.
Why do we say the Expert is a skill monkey? What does his class feature say? Everything the Expert has is for that role.
That is why we say these things about the Monk and Expert: because that is what they are set up for.
Every post you have made so far says the Monk isn't cut out to be front line melee guy, so that's a lie. And if your going to pull out the PHB and try to fine some flavor text to prove me wrong, flip over to the Sorcerer entry and read about how the Wizard+lying = face of the party.
Example of a different comparison.
A Monk can be a better scout than any Rogue base can be. At level 2 while the Rogue has to stop and scout a dark spot and maybe even watch guard patterns before moving pas a guarded perimeter the Monk goes invisible and just walks though the area. At level 4 he can gain Wall Walker. It's not outright flight, but in enclosed areas he fights in three dimensions a level before the Wizard does. At level 9 he mastered moving in three and learns to fight in four dimensions, again a level before the Wizard can (plane shift). Back at 7th level the Monk maintains his Full-Concealment even from effects like Lifesense and Spot checks, unless the creature has Blindsight, always 'fail'. Rogue doesn't have those, he buys flight and probably never had an interplanar thought in his life, but he does have Trapfinding. Oh yeah, if the Expert can blow a feat on that, surely the guy with three feats more than the Expert can too. So there is that, and immunity to poison, and better saves, and more HP, too. Heck, the Monk can pick up Tracking too and those DCs are trivial. In every regard, the Mink's Class Features (including ACF) makes him a better scout than a Rogue or even the Scout class.
Also on the terms of combat viability, the Rogue has SA which has to be front loaded with items and tactics to work, the Monk simply picks up charging and though Wall Walker does it in style. He can reliably trigger Battle Jump off a Move Action and follow up with a Standard Attack at level 4 for the equivalence of three attacks (battle jump is done at x2). This is done two levels before the game thinks having two attacks is great and yes in this tiny window he is a more reliable source of damage than the Barbarian. Both the Rogue and Monk sport the same hit chance, but should it be enough to hit for the task the Monk can FoF out for more attacks (and later FoFs anyway). Both cling to their combat nooks, SA and charging, like it's the only way to remain combat viable. As far as being one trick ponies and the weaknesses tied to it. The Monk has to deal with a distance clause (Battle Jump greatly fixes) and the Rogue has to front load SA with tactics & items and then it still won't always work. Charging in the overall has always been better than SA, it's easier to obtain & use and doesn't need the TWF to keep up.
The Rogue isn't deprecated of course. His greater skill base leads to adding on social interaction. Disguise, Bluff, Gather Information, the Monk really has nothing for this area outside of Diplomacy. For most people that turn to Rogues, they turn to them for the social interaction because the rest of the party ditched it in favor for being combat brutes and gods. So while the Monk can be better suited for scouting, the party really needs someone to apologize for the holes in the wall and keep the spell caster from dominating everyone and they go Rogue. It's back to Min/Maxing again, combat and spells covered. You need someone with skills, and to be a target of various buffs to tack on proficiency in any role you all lack.
