Prove it.
Here are my numbers:
Level 1 Human Thief
Dex(20) +5
Rogue's Trick: Acrobat's Trick, Tactical Trick
Background: Gritty Sergeant (Rapier)
Feat: Surprising Charge
Feat: Light Blade Expertise
As others have noted, I don't think that guy represents the average 1st level Thief. And I have one big issue with your math - assuming that the thief can regularly charge into Combat Advantage with Acrobat's Trick. I've found that getting CA for rogues isn't hard, but often involves shifting around an enemy. If your thief starts next to an enemy, you will not be able to back away and charge into the flank without taking at least one OA. Thus, a lot of your assume damage - from Acrobatic's Trick and Surprising Charge - is not available nearly as often as you are claiming. Sure, Acrobatic's Trick itself might be reasonable to use if you start your turn in flanking, but this idea about being able to bounce in and out of combat via move actions... not sure I buy it.
But sure, I'm game, let's see how the PHB Rogue measures up.
Level 1 Human Rogue, Brutal Scoundrel
Dex 20, Str 14
Silly Background = Rapier Proficiency
Backstabber, Light Blade Expertise
Piercing Strike with Combat Advantage: +11 vs Reflex 13: 3d8+8.
Damage: 0 (0 x 0.05 = Miss Chance) + 19.35 (21.5 x 0.9 = Hit Chance) + 1.6 (32 x 0.05 = Crit Chance) = 20.95 damage.
Our result does indeed come out behind your Thief. Under, admittedly, ideal circumstances for the thief that make some pretty significant assumptions about battlefield conditions - including the thief never starting in melee combat with a foe. That seems relatively unlikely to me. Shall we look at your thief's numbers under, say, more reasonable conditions?
First, though, I do want to note that the Rogue's damage is, undeniably, still twice what an average non-Striker will do. That was your original claim, remember - that this didn't happen prior to Essentials, and was a new thing. And it isn't true. The bugbear above was my very first 4E character. It was silly optimized, yeah, and the rest of the party totally noticed that it did stupid amounts of damage. And, of course, took absurd amounts in return, and was constantly limping around with too few surges - much like your thief will given his strategy of provoking OAs every turn.
Now, what would a more legitimate comparison be? Let's take the charge assumption out of the equation - it is occasionally available to the Thief, but hardly something you can rely on.
Level 1 Human Thief
Dex(20) +5
Rogue's Trick: Acrobat's Trick, Tactical Trick
Feat: Backstabber
Feat: Light Blade Expertise
Basic Attack with Combat Advantage : +11 vs AC 15: 1d6+2d8+10.
Damage: 0 (0 x 0.15 = Miss Chance) + 19.125 (22.5 x 0.85 = Hit Chance) + 1.6 (32 x 0.05 = Crit Chance) = 20.725 damage.
So, ignoring the charging build, these guys are coming out basically the same. Acrobatic's Trick gives the Thief the slight edge in raw damage, while the Rogue has the edge in accuracy, coming out fractionally ahead in total DPR.
In the other arenas, I will certainly admit the Thief's tricks give an edge on being able to get CA with ranged attacks while immobilized. Does this mean that the Thief will always have CA when the rogue does not? Not at all, unfortunately - the main element I have found that deprives Rogues of CA is being Dazed, and that shuts down the Thief just as handily.
Theorycraft, of course, won't be able to show us the exact breakdown on how often Rogues are unable to get CA and how often the Thief will have it in their place. From my experience, the big advantage will be for ranged builds - and even then, well-built Rogues can get CA just about as reliably as Thieves. So perhaps the actual benefit will be for melee builds who get
stuck at range, which just is not that common a scenario.
And, finally, if you trick out for a charging build... then, yes, the Thief can eke out an extra 3 points of damage in rounds in which he can safely charge with Acrobatic's Trick. Not that huge, and balanced against other harder to quantify benefits for the Rogue like the usefulness of Encounter and Daily Powers.