Thing is, 'eight commoners in a mob' is the exact type of group that would run in terror from the dragon. It's not military organisation in that case, it's clumping people together and hoping for the best. Honestly, this is what's weird: a mob gains all the morale and cohesion benefits that require military training and drills to achieve (complete immunity to basically every effect short of fireballing them to hell and back), despite it being a hell of a lot easier to disperse, say, the drunken contents of a pub than a smaller military unit.
I will freely admit that this is possibly my least-favourite thing out of everything of yours that I've seen. Damage sponges that automatically deal damage, are basically immune to all effects, and (if an NPC is in charge), can easily gain a powerful NPC that's got massively inflated defences from the people around him? Oh, and if the leader has any high mental stat score, the mob also gains huge benefits.
Then you get led units, which get to use special abilities as well as almost all of the defences and the ability to damage anything within reach...
I dunno, I just wouldn't think that 'make groups of weak creatures more threatening' would basically be making them vastly more annoying to deal with than most creatures of the same CR, just on the grounds that sheer damage dealt is the only applicable way to down them and most class abilities become... well, irrelevant. It just becomes a race to deal damage against something that can have... what, 90 HP whilst still being CR 3, and deal 6d6 damage automatically? Or 6d8 from anywhere within 120', moving back 20' each time. :/
Just seems kinda... draggy. And bland.
Blah. Should've written this post out ages ago, when I first got linked to it.