Let me get this straight, you're arguing that Warlocks dealing more damage than Rogues thanks to an extremely tenuous CustServ ruling (whose credibility you yourself have attacked) is not broken because 120 damage is pretty weak for a level 29 power.
First off, it was 118 damage + mods which also didn't include the bonus damage on a critical hit that implements grant. Even with a Pact Blade that's something in the neighborhood of 150 final damage. Then, on top of that, the target is removed to a separate plane of existence for up to 4 rounds, depending on how long the Warlock maintains the power. Then, when the target comes back, they are prone and stunned (save ends).
As for how hard it is for a Warlock to gain Combat Advantage, all that needs to be done is to Daze the target and then it gives CA to everyone.
Oh, and lets not forget, Solo Monsters are designed to take these hard hits, and really it is dangerous for them to do so. If Orcus takes 150 damage from each of 5 party members, then he's suddenly Bloodied already in potentially a one-round span, not to mention the battery of conditions he is now invariably is suffering from.
You do realize we're talking about a 1/20 chance vs. a 3/20 chance of this event, and not the impossibility of this at all?
And we're talking about a class whose raison d'etre is to deal damage. You're a striker, if you can't potentially do enough damage in one round to make an enemy sit up and take notice, you suck. Period. You're burning your best daily power, an encounter ability (multiclass sneak attack), and apparently we're comboing off another power use to achieve combat advantage. And 17/20 times we do less damage or miss! The expected DPR is much less than 150.
Not all the party is going to be strikers or you have other problems. Non strikers should be dealing less damage. Further, not all the party will be hitting. And if everyone burns their best daily in round 1 of a fight I expect whatever they're targetting to be in a world of hurt afterward. That's some serious resource expenditure on the part of the party and if its not rewarded then there's something wrong with the game.
Broken is achieving damage in excess of that at level 11 with encounter powers (ie, Blood Mage). This is a combination of a power, a PP, a multiclass feat feature, and a particular implement type (dagger pact blade) with a top-tier 1/day power, and happens about 15% of the time. Knocking off 1/10th of Orcus's hp sounds, if anything, a little lackluster. I'm pretty sure Blade Cascade + Imperiling Strike, using the errataed version, does better than that. Heck, a Minotaur Fighter with a maul can do max(14d8)+mods 10% of the time with a level 29 daily, which is 112 + mods, and could well include multi-rogue for SA, power attack, and so forth - passing 150 pretty handily. And he's not even a striker. So heaven forbid a striker using a number of abilities, feats, class features, and a top tier power manage to only slightly underperform a minotaur maul fighter.
(Even without SA, the maul fighter gets 112 + 6d12 (vicious maul) + str (9) + power attack (9) + choice of wisdom (pit fighter)/possibly con (if knocks prone, iron vanguard)/4 (kensei) + 6 enhancement = 179 average assuming kensei. And I've left out things like weapon focus - you can probably add another 5-10 with feat choices)
Edit: I keep wanting to divide parts of my probabilities in half. I think they're right now. I must be tired, I can't add constants together.