Falling Icicle
Adventurer
I think there is plenty of room for debate here.
With flatter attack/AC math and larger damage/HP spread, a kobold is never a life threat to high-level PCs, but is always a penalty for them (by grinding their HP a little).
Consequences of this are that tossing a kobold into an encounter always makes a difference, small but totally under control, hence you can (if you want) still feature kobolds in your game at all levels. Second consequence, lots of kobolds together can become also a large threat (but here I want to see how they manage to make the encounter easy to run... probably mob or swarm rules at some point).
The opposite approach: large attack/AC spread and small damage/HP spread. This leads to kobold forever being a life threat (they can kill you in one or few blows) but more and more rarely (need a roll of 20 to hit).
Consequence is that probably encounter design is more difficult... if you toss a kobold or two into a high-level fight, it's not so easy to predict their effect.
However D&D was never this second case. There has always at least be a large HP spread (even in old D&D, although HP at some level go up very slowly, but still this is only after level 10) so typically both the attack bonus/AC and the damage/HP spreads have been large. WotC just wants to avoid having this because it makes monsters obsolete early in the game.
The way I see it, having lower level creatures/characters do way less damage and having way less hp than higher level ones makes them just as irrelevant. It's fine for those things to scale, I'm not suggesting that a 20th level character should have the same hp and damage as a 1st level one, I just prefer that difference not be too extreme. What do I consider "too extreme?" Well, high level characters that have so many hps that they can laugh off the maximum damage from falling from any height, or that can survive being dunked in lava, are good examples.
In a combat-centric game yes, especially if combat is usually reduced to attrition, but on a game that features the other pillars on par with combat, or at least a game where combat is more dynamic and damage is just the simplest tactic but often not the best, then even a 4x damage output can be fine.
I wouldn't have a problem with such large numbers for ED, if it was only the Fighter: it's the most combat-focused class so it allows someone to be extremely good at fighting at the cost of lacking in everything else. I am instead not so much in favor of damage boost to spells and abilities of all the other classes.
I think that attempting to balance character classes across pillars is a terrible idea. A fighter shouldn't be 4x better than a wizard in combat becuase the wizard is 4x better in the exploration or social pillar. For one thing, what if I'm an evoker type wizard that focuses on combat spells and has few or no social or exploration magics? Why should that character suck just because he could have chosen the other options? Trying to balance a character's weaknesses and strengths across pillars is a doomed exercise. They're apples and oranges, and one does not in any way equate to the others.
All character classes need to have a certain degree of basic competence in all three pillars, IMO. To me, it's simply unaccaptable to just let wizards suck in combat or just let fighters suck at exploration. Players shouldn't be left twiddling their thumbs during 1/3 or 2/3 of the game because the class they chose sucks at those things and can't meaningfully contribute. Right now, fighters do suck at the other two pillars. But that needs to change! Make fighters better at exploration and interaction. Don't make wizards pay for a fighter's design faults by making them suck at a pillar too.
Besides, wizards have traditionally been the glass cannon class, able to do incredible amounts of damage but paying for it with pitifully low hp, inability to wear armor and other such weaknesses. That, and it just doesn't make sense to me that a wizard throwing around fireballs and bolts of lighting should be inflicting significantly less harm than swords and arrows.