I am a fencer - I melee via Dex (like a rogue) - I am pretty good at it (made the Uni team etc).
If someone shouted at me to "Hit him right now!" I would not do a good job of it. I make my attacks by fienting, drawing the opponent, swinging my blade about to confuse etc. I don't just take a reckless swing, which is what I think of for the Leader's granted attacks - they are quick (free action) and unconordinated with my typical style (MBA not a class power). ~As for charging, well fencing has it's own version of a mini-charge (the lunge) and when most fencers do a full on charge it has about a 70% chance to get them hit rather than the revesre as it forgoes all the finesse and poise normally used in their attacks. So the idea of someone who has a Dex-based melee style being bad at MBA's is hardly unthinkable to me.
A good fencer can react as well as act. Reacting is basic attacks. As a fencer I imagine that if your opponent stopped to pull something out of his fanny pack (provoking an oppurtunity attack in game mechanic terms) that you would make him pay for it. The riposte portion of risposte strike is str, meaning that per d&d rules ripostes are even harder to do for a dex character than wild swings, (as melee training doesn't technically fix this) the best riposters in the world are hulking 250lb behemoths, go explain that to your fellow fencers. At the end of the day the question isn't whether you are good at charging, or swinging when your coach yells at you etc., it's whether tacking on 30lbs of lean muscle would make you better at it (it wouldn't, at least not noticably).
Real world arguments all fail to grasp that oppurtunity attacks are a game mechanic. In the real world there are held actions, actions, and rushed actions. And that is it. If guy B turns his back on me while I am parrying Guy A, no free attack. Just the way it is. For that matter there is never a free attack. It takes a certain amount of time to swing the sword (this can vary, again between held and rushed, light tap and haymaker, but the variance is not 100% or 0%, but more like 80%-120%). Someone shouting never makes me swing a sword faster. Again just the way it is.
Now in a real fight you don't come anywhere near your swing limit (fencing comes closer than other types of fighting, though it is still doubtful you spend much time at your physical limit). Instead of [swing swing swing], real fights are [wait, approach, wait, eye feint, block, swing]. I could, if presented an opportunity too good to pass up (say my opponent goes digging in his fanny pack for a "potion"), squeeze an extra attack or two into the sequence, but the oppurtunity would still need to come at the right time. How much I can bench press would not impact the quality of those swings in any relevant way, actually, a nimble fighter would be better at taking advantage of such openings than a brutish one.
Real world combat is more hollistic than I use str, you use dex, but D&D is a game. It simplifies certain things and exphasizes differences in broad strokes. I respect that, enjoy it even. But I do find the fact that nimble rogues suck at risposting, or striking when someone lets their guard down, to be a clash between reasonable expectations, and mechanics.