KD,
I would be interested in what makes you feel that intimidate is game breaking to begin with. Given what R1 said above, there are so many situations that intimidate just doesn't fly with that I don't understand your reasoning for calling a once-per-encounter ability to make a foe surrender game breaking.
First off, Intimidate is not once per encounter. It's a max of once per encounter per bloodied foe. The PC can do this several times in a single encounter against different sets of bloodied foes.
You'll note that several people here stated that they have never seen Intimidate used in their game. There is a reason for that, but it isn't the +10. The reason is that many players understand the uberness of Intimidate and do not create such PCs.
There are players who want to play "save or die" type PCs (such as Orbizards or Intimidate builds), but very few players do so.
As was shown by renau1g, it is fairly easy to get a high Initimidate skill. Still, few players do it. The main reason is because it feels a bit like cheating to lock down a foe or make it surrender without doing enough damage to it.
In the case of normal Intimidate, say a player took the skill and had a Cha of 18. That's a total of +9. The chance of success at first level against same level foes is 30% to 45%. A 50% to 60% chance to damage a foe, or a 30% to 45% chance to taking the foe out completely.
That still seems a bit cheesy, but not so bad.
Now, up the 30% to 45% to 45% to 60% with a feat like Skill Focus Intimidate and the choice becomes a no brainer. 45% to 60% chance to force a foe to surrender, or a 50% to 60% chance to damage a foe (and of course, multiple foes can simultaneously be attacked with Intimidate without any real range limit).
Skill Focus Intimidate is bad enough. Replace it with New Sarshel Enforcer and it becomes amazingly good.
Sure, the player could roll a 3 and a 6 and get zip for it. But there will be so many times that at least one of the two dice will be 15 or higher (51% of the time or half of the foes it is used against) that it becomes extremely problematic.
The PCs wipe out the encounter in 3/4ths the time. And that's with a single feat, let alone taking both of the feats.
One really has to understand Action Economy to understand how uber Intimidate really is straight from the book. Taking out one bloodied foe changes it from 5 on 5 to 5 on 4 and decreases the encounter by a half of a round (and uses slightly less resources, especially healing surges). Changing it from 5 on 5 to 5 on 3 decreases the encounter by a round. This could be fairly common. And this is with no expenditure of resources, in fact, it saves resources.
Now, throw in a Kalashtar PC (like CaBaNa's new one) and although the range is now limited to 5, there is never a +5 penalty to the roll for not understanding the language (course, literally by RAW this does not work since Intimidate states speak and not communicate, but I suspect most DMs would allow it).
Even given the uber focused build you described with a +17 to intimidate, the likelyhood of it being abusive is well, not likely. Compare this with the striker who has focused purely on damage. If a standard creature is at 1/2 HP, even given the case that it is an N+4 creature, you're looking at an average of 25-30 additional hit points. I've seen SEVERAL strikers dish out over 25-30 damage in a single encounter power.
Sure they can (typically not at level 1 though, it usually takes several feats and some magic items to get this). Does that mean that it is balanced for any non-Striker to do Striker level equivalent damage against multiple foes with basically unlimited range and not using up a resource?
To me, it's not just Intimidate by itself. It's Intimidate combined with 2 D20 rolls. That's when it becomes extremely problematic. That's when it will work in many more encounters.
When there are 3 bloodied foes and the PC with Intimidate has a good chance of taking out 2 or all 3 out of 3 of them with a single Standard action.
This isn't like your uber Perception PC that noticed a lot of stuff. This is the equivalent of a multi-target Daily power that does a ton of usable multiple times every single encounter.
Intimidate is badly designed, but most players do not use it because it is so cheesy. New Sarshel Enforcer is worse. Instead of 11 or higher 50% of the time, it's 15 or higher 50% of the time. And it stacks with Skill Focus Intimidate.
And Will defense isn't exactly the highest defense for the vast majority of creatures.
The counter question I would ask is: Given the problematic nature of Intimidate (assuming it is problematic, but not broken), why would you want to vote in a rule that makes it even easier to use?
As a DM here, just like I would not allow an Orbizard into my game, I wouldn't allow an Intimidate build either. But that's just me. I like the PCs to be challenged without them having a go to the well ability to take out foes that turns a normal non-Striker into an uber Striker without using up any resources.
PS. Go look at CaBaNa's PC. It has an Intimidate of +21 at level 4 (with same level foes with Will +10 in the 25 to 28 range, in the 29 to 33 range for N+4 foes) and it is a Kalashtar. What a monster!!!
LEBC:Veruza Jeleka (CaBana) - ENWiki
I have no issue with CaBaNa playing such a PC. That's between him and his DM. But to make that PC or any PC even more capable with Intimidate seems illogical and a bit unfair to the other PCs and the DM.