I guess huge is a matter of opinion. The final balance pass was after the last playtest so it's possible that the numbers are closer. However, even if they aren't, doing 70% of fighter's damage is pretty close. Not only that but given the fighter is making 4 attack rolls to get that damage the chance that he gets less than 100% is much higher than the Rogue. I'm not sure how to do the exact calculation but it's likely that the Rogue does more than 70% of the fighter's damage because of this.
Actually, no.
An Archer Fighter (Warrior) has a +1 to hit over a Rogue, Crits on an 18-20 at that level, those criticals do significant additional bleed damage (piercing), and most importantly, benefits from static damage modifiers multiple times - so his Longbow +4 (say) adds 4 to EACH attack he makes, whereas it only adds it once to the single attack of the Rogue.
Let's say the base chance to hit is 60%
So he's looking at 1d8+9, with a 50% chance to hit, a 15% chance to hit AND crit (which effectively does +8 damage when it happens), and he makes four attacks. We'll ignore the bleeding for simplicity's sake. Average of 1d8 is 4.5 so +9 is 13.5. 50% of 13.5 = 6.75, but as there is the chance of crit we add in (13.5+8 = 21.5)*0.15 for an average of 9.975 (can we call it 10?

) damage per attack (with misses and crits factored in - so the Fighter averages 40 damage (ignoring bleeds etc., which will actually add up but god we have to stop somewhere).
Archer Rogue also does 1d8+9, and has a 55% chance to hit, and a 5% chance to hit AND crit (which effectively does +8 damage when it happens), and he makes one attack. He adds +7d6 on a hit (avg. 24.5) if the enemy is distracted, which we will assume that they are. We will ignore Death Strike and Assassinate as they are once-per-combat abilities, working as they do on only on Surprised targets (but we can look at that math later if interested). Not sure if crits maximize SA, will assume they don't (doesn't make a huge difference with only a 5% chance). Anyway, 13.5*0.5 = 6.75, +21.5*0.05 = 1.075, let's be generous and call it 8. SA is 24.5*0.6 (ignoring crit) so 14.7, call it 15. So 15+8 = 23.
So the Rogue actually only does 57.5% of the Fighter's damage.
That's still close, right, 57.5%?
An additional wrinkle is the fact that the Rogue is somewhat more likely to have Advantage on his attack. I honestly do not know how to factor this in. I am willing to accept that it might take the Rogue closer to 70%, but I still don't find 70% to be "close". You could get away with calling 85-90% "close", but 70%? No.
With two-weapon fighting it gets even more complicated. The Rogue becomes more likely to deliver their SA, but the static bonus on the Fighter's damage increases further (see Fighter abilities), and then the Fighter's greater survivability becomes more of an issue, and the Rogue will find it far harder to get Advantage, because you're in melee.
I guess when I'm used to the difference in 3e being nearly 100 points between the weakest and strongest person in the party, 15 points seems small and insignificant by comparison. The difference was much bigger than 15 points for most characters in 4e as well.
3E was so bad here that I would never, ever run it again (play it, yes, but only with near-tier characters). That was just unacceptable. In 4E, different roles did different damage, sure, but there you didn't get a class that, by default did more damage, was more survivable, and had greater control that another class.
Again, we're not talking 10 or 15%. We're talking 30-40%. If Rogues did 10% less, whilst
also being less survivable, and
also having less control, I'd probably roll my eyes a bit but I think it would likely be okay. But they don't - they do 30-50% less as of the October packet.
It has not been our experience in the game so far that the Rogue has felt anything but powerful. They do more damage by far on an average round than the Cleric or Wizard.
The average combat for us generally goes like this at 5th level:
Fighter hits one of his two attacks and does 14 damage
Wizard uses a cantrip and the enemy makes his save
Cleric uses a cantrip and the enemy fails its save doing 9 damage
Rogue hits doing 13 points of damage
The enemy goes, the fighter is already in melee and did the most damage so they attack the fighter. The fighter takes 20 damage and the round starts over.
That's lovely, but it's meaningless, sadly. There is literally no value in taking a single round and saying "that's how it generally goes".
Anyway, all my stuff is kind of meaningless too (in a totally different way), because neither of us know what Rogues look like now. A few tweaks could easily have put them within 10-15% of Fighter damage, and I certainly hope that that happened.
EDIT - Surprise round addenda - Because the gap is so big, and Death Strike can be saved against, I kind of suspect that our two archers do pretty comparable damage even the Rogue is supposedly in his element. I haven't done the math on this yet, though.