See? Now that is the camp I am in when it comes to play/combat balance. I honestly don't care. I make a specific encounter to be of a specific level of difficulty. Period. You wanna come along and go into the Goblin Warrens at level 10 instead of level 3? Hey, it's your party, pal.
That said, I think having MOAR Goblinz isn't such a bad idea for higher level players. And, do take into account that goblins in a large warren will have goblin guards, goblin shamans, goblin lieutenants, goblin captains and goblin priests which can vary (and here I am going to show my D&D age a bit) between 1/2 to 2 HD for goblin fodder, 2-4HD for the guards, 3-6HD for the shamans, and priests and 5-8HD for the lieutenants, captains and the goblin king.
And don't forget, goblins breed like rats, or flies, or well, goblins. So there's gonna be a lot of 'em.
If I had to balance it, I'd set a quest for lower level characters that only had to go into the hills and scout out the goblin situation, find their entrance and report back to HQ. In this way, if they take on that quest, that's all they get to do and if they try to approach the entrance to the warrens, you get a triggered convo box that says, "The entrance to this cave is heavily guarded by at least 2 squads of goblin guards. You realize it would be foolhardy to reveal yourselves at this time and you wisely scuttle away quietly so as not to attract their attention." And you just don't allow the characters to enter, based on a Level Check that's either tied to their quest journal or is a simple Pass/Fail of their overall party level.
Now that's how I'd do it for NWN2. As a PnP designer, I'd have the DM inform a very low level party that the entrance looks to be heavily guarded and entry would be, at best, foolhardy. Now if they want to enter anyway, well, like I said, hey pal, it's your party.
The same should hold true in some cases for encounters well above your party's ability to handle. You want to enter that cave with all the indicators that possibly a very large and very unruly creature lives inside? Sure, go ahead. Don't say you weren't warned. If you choose to enter the cave and then run into a nest of Wyverns or a single Dragon and you get your butts handed to you, well, you knew the job was dangerous when you took it. Hope you saved before entering.
I like to worry less about overall party level balance and encounter balance. I spend my efforts on creating a story within a framework that, hopefully, self corrects by gently leading the PC(party) along some greased rails with occasional stops on the sidings and time for snacks, shopping and some souvenirs before getting back onboard.
I try not to be too heavy handed when it comes to where should a PC go next. Hey, your quest journal was just updated and you just talked to the guy that said where you were supposed to be going, so if you don't want to go that way, well then don't complain that the story doesn't unfold in a consistent or logical manner. You went the wrong way on purpose, I didn't lead you astray.
So I am not a big fan of scaling, per se, but that's my far and distant D&D roots (and general intransigence at changing a good thing) showing and not necessarily an inability to see it's potential and value under the correct conditions.
dunniteowl